JP2892516B2 - Nonlinear optical fiber and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonlinear optical fiber and a nonlinear optical device using the optical fiber, and more particularly, to an optical switch, an optical memory, or an optical switch to be used in optical data / information processing or optical communication systems in the future. The present invention relates to a non-linear optical device such as a signal processing device and an optical fiber used in the non-linear optical device.

[0002]

2. Description of the Related Art The nonlinear optical effect is an effect that occurs because the electric polarization P in a substance has higher-order terms of E ² and E ^{3 in} addition to a term proportional to the electric field E of light as described below.

P = ０００３ ⁽¹⁾ E + χ ⁽²⁾ E ² + χ ⁽³⁾ E ³ (1)

In particular, the third term indicates the third harmonic generation (phenomenon of emitting light of frequency ω), which is well known as a third-order nonlinear effect, and depends on the intensity of light represented by the following equation. This causes a change in the refractive index.

N = n ₀ + n ₂ I, (2)

[0006] n ₂ is the third-order nonlinear susceptibility χ ^{(3) of the} equation (1),

N ₂ = 16π ² χ ⁽³⁾ / cn ₀ ² (3)

Here, n ₀ is a linear refractive index, and c is a light beam.

When this optical medium having the third-order nonlinear optical effect is combined with another optical element such as an optical resonator, a polarizer, or a reflector, an optical bistable element, an optical control optical switch, an optical modulator, Alternatively, important devices used in the future in optical information processing and optical communication systems, such as a phase conjugate wave generator, can be constructed.

A conventional example of an optical Kerr shutter switch, a fiber loop mirror switch, and a Mach-Zehnder switch among the nonlinear optical devices utilizing the nonlinear refractive index effect will be described below.

As shown in FIG. 1, an optical car shutter switch gates input light with gate pulse light,
This is to obtain output light corresponding to the time waveform of the gate pulse. In the figure, an orthogonal polarizer system composed of two polarizers 2a and 2b arranged so that their polarization axes are orthogonal to each other, and 1 is a CS ₂ conventionally sealed in a glass cell having a length of 1 mm. (Carbon disulfide) liquid. In this configuration, the linear polarization of the input light that has passed through the polarizer 2a changes to the elliptical polarization due to the change in the refractive index of the nonlinear refractive index medium 1 only while the gate pulse P _g is incident.
Therefore, a part of the light can pass through the orthogonal polarizer 2b. That is, the input light is optically switched by the pulse of the gate light.

Instantaneous transmittance T of input light and phase change Δφ
Is maximum when the polarization direction of the gate light and the polarization direction of the input light are inclined by 45 °. in this case,

T = sin ² (Δφ / 2), (4)

Δφ = 2πn ₂ LI _g / λ (5)

## EQU1 ## Here, L is the medium length, λ is the input light wavelength, _Ig is the gate light power density, and n ₂ = 16π ² χ
⁽³⁾ / cn ₀ ² is a nonlinear refractive index.

When Δφ is sufficiently small in the equation (4),

T ∝ χ ⁽³⁾ L ² _Ig ² , (6)

[0018] because made, T is χ ^(3), L and seen to be proportional to the respective square of I _g. From now on, in order to reduce the required gate light intensity, it is necessary to use a high-efficiency material, increase the interaction length by increasing the length of the medium, and increase the light density by reducing the spot size of the beam. It can also be seen that the use of a fiber-like medium is effective. Also, when trying to obtain the same value of the transmittance T, that is, the same value of the phase change amount Δφ,

I _g Ｌ L ^-1 (7)

It can be seen that there is the following relationship.

As a result of the applicants' additional tests of a conventional CS ₂ optical Kerr shutter, λ = 0.83 μm and L = 1 m
When m and I _g = 300 MW / cm ² , an instantaneous transmittance T = 0.4% was obtained. From this result, (4),
When the nonlinear refractive index n ₂ is calculated using the equation (5),

N ₂ = 3.1 × 10 ⁻¹⁴ cm ² / W, (8)

Is obtained. When the nonlinear susceptibility χ ⁽³⁾ is calculated from this n ₂ value,

Χ ⁽³⁾ = 1.6 × 10 ⁻¹² esu, (9)

Is calculated.

It has been confirmed that the response speed of this CS ₂ optical car shutter shows a high-speed response on the order of picoseconds. Therefore, it is widely used in measurement systems such as instantaneous photography and high-speed spectroscopy. However, as shown in the equation (7), there is a disadvantage that the nonlinear efficiency is not always large, and therefore an extremely large gate light intensity is required.

As a fiber loop mirror switch,
For example, KJBlow, NJDoran, BKNayar, and BPNels
One using a silica-based fiber as shown in on OPTICS LETTERS Vol. 15 (1990) 248 is known.

As shown in FIG. 2, this non-linear optical device is intended to control the destination of a signal light having information or the waveform of the signal light by another control light. As shown in the figure, an optical coupler 23 that divides the signal light 21 incident on one incident end into two exit ends almost equally, a quartz-based fiber 24 connected to the two exit ends of the optical coupler, and the like. The main part of this device is constituted by an optical medium having a nonlinear refractive index effect of And
For example, by giving the optical coupler 23 a characteristic that the control light is emitted to almost only one emission end,
A structure is provided such that the control light propagates only in one direction in the optical medium having the nonlinear refractive index effect. When the control light is not incident, the signal light incident on one of the incident ends of the optical coupler 23 is almost equally divided by the optical coupler 23 and propagates in the nonlinear optical medium in exactly the same distance in the opposite direction to the optical coupler 23. Come back. Then, due to the interference effect of the signal light propagating from both directions in the optical coupler 23, the signal light is emitted to the incident end where the signal light is incident (25 in the figure). On the other hand, when the control light is incident, of the signal light propagating in the nonlinear optical medium, the signal light propagating in the same direction as the control light undergoes a phase change due to the nonlinear refractive index effect of the control light. This phase change amount Δφ is given by the following equation.

Δφ = 2πn ₂ LI _in / λ (10)

Here, L is the medium length, I _in is the power density of the control light, and λ is the wavelength of the signal light. Therefore, a phase difference is generated by a phase change amount Δφ between the signal light propagating in the non-linear optical medium in both directions and returning to the optical coupler 23, and the signal light is applied to the other incident end of the optical coupler 23 by an interference effect. It is emitted (26 in the figure). At this time, the ratio T of the signal light emitted to the incident end is given by the following equation.

T = sin ² (Δφ / 2) (11)

Therefore, if the control light is incident so that the amount of phase change Δφ becomes π, the signal is completely emitted to another incident end. However, also in this optical device, since the nonlinear refractive index effect of the silica-based fiber used as the optical medium having the nonlinear refractive index is small, with a small light intensity,
In order to realize an operation in which Δφ becomes π, several hundreds are required.
In this case, a very long quartz fiber having a length of at least m or more is required, resulting in a problem that the element size becomes very large, and that the operation of the element becomes unstable.

Conventionally, the Mach-Zehnder switch is the same as that shown in FIG.
As shown in FIG. 1, those using the electro-optic effect of lithium niobate have been manufactured. In FIG. 3, reference numeral 31 denotes a core formed by thermally diffusing titanium into a lithium niobate substrate 32, and reference numeral 33 denotes an electrode. Lithium niobate is an optical crystal having an electro-optic effect, and its refractive index can be changed by applying an electric field. For this reason,
With the configuration shown in FIG. 3, when the two branched lights are multiplexed due to a change in the propagation coefficient of light propagating in the core caused by a change in the refractive index due to the electric field, the position between the two lights is changed. A phase difference occurs. As a result, the output light intensity changes in accordance with the phase difference due to the interference, and thus, by changing the potential applied to the electrode, it functions as a switch. However, a switch using such an electro-optic effect is limited by stray capacitance in an electric circuit.
There is a disadvantage that it is not suitable for use as a high-speed switch. Therefore, in this Mach-Zehnder switch, it is desired to use an optical control optical switch without these limitations. However, this is also a problem similar to the above two types of switches, that is, a high-efficiency material is used. There was no problem.

Therefore, an optical medium having a large nonlinear optical effect and a small light intensity required for operation has been eagerly desired, and active research and development have been promoted. As a result, an optical fiber made of glass to which semiconductor fine particles are added, and an optical fiber containing a highly efficient organic crystal have been developed. However, also in these, there are many problems in terms of light transmittance, optical waveguide structure, and the like.

In the case of an optical fiber made of glass to which semiconductor fine particles are added, the nonlinear optical effect is 10 ⁴ to 10 ⁵ times greater than that of SiO ₂ , but the light absorptance at the operating wavelength is high. Because of the large size, the element length must be extremely short, and it is difficult to obtain a large nonlinear optical effect after all.

In the case of an optical fiber in which an organic crystal is sealed, there are advantages that the nonlinear optical effect per unit length is larger than that of quartz glass by 10 ² or more, and that the light absorptivity at the operating wavelength is small. However, due to the non-uniformity of the organic crystal and the like, the light transmittance and the linear polarization of the incident light are inferior, and the fine adjustment of the refractive index difference between the core portion and the clad portion of the optical fiber is completely performed. It is difficult to perform the process uniformly over the range, and therefore, there is a problem that it is difficult to form an appropriate optical waveguide structure and increase the light intensity.

[0037]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized in that a nonlinear optical fiber has the following three structures.

(1) As an optical medium having a nonlinear refractive index effect, a hollow portion is provided in a small-diameter tube mainly composed of glass, and an organic substance having a nonlinear refractive index effect is converted into an organic solvent or a polymer material having excellent transparency. The dispersed organic matter dispersion is sealed in the hollow portion to form the core portion b0, and by adjusting the dispersion concentration or the composition of the dispersion, the refractive index of the core portion becomes larger than the refractive index of the cladding portion. (Hereinafter referred to as (1) type nonlinear optical fiber).

(2) An organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency, and the refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion. In a nonlinear optical fiber in which the body is sealed in a hollow small-diameter tube mainly composed of glass, the refractive index equal to that of the organic dispersion is mainly composed of glass having a hollow portion for sealing the organic dispersion. A core a1, a core b1 made of the organic dispersion encapsulated in the center of the core a1, and the core a1
(Hereinafter, referred to as a (2) type nonlinear optical fiber).

(3) An organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency, and the refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion. In a nonlinear optical fiber in which the body is sealed in a hollow small-diameter tube mainly composed of glass, the refractive index equal to that of the organic dispersion is mainly composed of glass having a hollow portion for sealing the organic dispersion. A core a2, a core b2 made of the organic dispersion encapsulated in the center of the core a2, and a core a2
And a clad having glass as a main component and having a refractive index smaller than that of the core a2, and at least two stress applying portions mainly containing glass arranged in the clad, wherein the stress applying portion is Facing each other across the core a2,
In addition, the core a2 is separated from the core a2, and has a structure in which the thermal expansion coefficient of the stress applying portion is different from the thermal expansion coefficient of the clad and applies a non-axisymmetric stress to the core a2 (hereinafter referred to as (3) type nonlinear optical fiber ).

Next, the nonlinear optical device has the following configuration.

(4) In a nonlinear optical device in which an optical medium having a non-linear refractive index is sandwiched between two polarizers arranged so that the polarization axes are orthogonal to each other, the optical medium having a non-linear refractive index is defined as (1) , (2) and (3) type nonlinear optical fibers.

(5) A semi-transparent mirror or optical coupler having two entrance ends and two exit ends, and for dividing the signal light incident on one entrance end into two exit ends almost equally, and the semi-transparent mirror Alternatively, in a nonlinear optical device having a structure in which an optical medium having a nonlinear refractive index effect is connected to two output ends of an optical coupler and having a structure in which control light propagates in the optical medium in almost only one direction, the nonlinear refractive index is reduced. A configuration using the above-mentioned (1), (2), and (3) type nonlinear optical fibers is used as the optical medium.

(6) One light beam is split into two light beams by a semi-transmissive mirror or an optical coupler and passed through different paths to give a relative optical path length difference, and then the two light beams are combined again. The optical device to be used has a configuration in which the above-mentioned (1), (2), and (3) type nonlinear optical fibers are used as an optical medium having a nonlinear refractive index.

Further, the non-linear optical fiber of the present invention is a styrene derivative of 4- (N, N-diethylamino)-. Beta.-nitrostyrene (Kurihara, Kaino "New organic non-linear optical material") as an organic substance having a non-linear refractive index effect. DEANS
T "50th JSAP Scientific Lecture 28p-ZP-1
(1989), and Kamihara, Kobayashi, Kuboji, Kurihara, Kainou, "Optical K using a novel organic nonlinear optical material DEANST"
err shutter operation ”, Lecture 28p-ZP-2, hereinafter referred to as“ DEANST ”, and 4′- which is an ionic crystal material.
Methosulfonate salt of dimethylamino-N-methyl-4-stilbazolium (Kamihara, Kobayashi, Kuboji "High-efficiency optical Kerr shutter operation using organic material" The 36th Joint Lecture on Applied Physics 2p-G14 (1989), Below D
Examples using MSM) and terephthal-bis [(p-diethylamino) aniline] (hereinafter, referred to as SBAC) which is a tricyclic benzylidene aniline derivative are shown in Examples, but other organic substances having a nonlinear refractive index effect are also shown. The third-order nonlinear susceptibility χ ⁽³⁾ The molecular crystal material having a value of 1 × 10 ⁻¹³ esu or more, the ionic crystal material, or the transparency in which these crystal materials are contained or bonded in the molecule. It is characterized by using an excellent polymer material, a π-electron conjugated oligomer or a polymer material, or a combination thereof. Examples of such organic substances include 4-nitroaniline (p-NA) and 4- (N, N-diethylamino) nitrobenzene (p-DEANB), which are molecular crystal materials that have been conventionally studied as nonlinear optical materials. , 2-methyl-4-nitroaniline (MNA), 4-nitrophenylprolinol (NPP), 4-cyclooctylaminonitrobenzene (COANB), N-cyanomethyl-N-methyl-
Nitroaniline such as 4-nitroaniline (CMMNA) and its derivatives, 4-cyclooctylaminonitropyridine (COANP), 4-adamantaneaminonitropyridine (AANP), 2- (N-propynol)-
Nitropyridine derivatives such as 5-nitropyridine (PNP), 4-methoxy-4'-nitrostilbene (MN
S), 4-bromo-4'-nitrostilbene (BN
S), 4- (N, N-dimethylamino) -4'-nitrostilbene (DMANS0, 4- (N, N-diethylamino) -4'-nitrostilbene (DEANS), 4-
(N, N-dipropylamino) -4'-nitrostilbene (DPANS), 3-methyl-4-methoxy-4'-
Nitrostilbene derivatives such as nitrostilbene (MMNS), 4- (N, N-dimethylamino) -4′-nitroazobenzene (DMANAB), 4- (N, N-diethylamino) -4′-nitroazobenzene (DEANA)
B) or a benzoheterocyclic derivative such as 5-nitroindole (5NIN) or chloronitrobenzoxadiazole (NBD-CI), or 4'-diethylamino-N which is an ionic crystal material -Methosulfonate salt of methyl-4-stilbazolium (DESM), 4'-diethylamino-N-
Iodine salt of methyl-4-stilbazolium (DESI)
A dialkylaminostilbazolium derivative such as, and a pyridinium derivative, an azulenium derivative, a quinolium derivative represented by the structural formula shown in Table 1, or a polydiacetylene derivative which is a π-electron conjugated polymer material,
Poly (paraphenylene vinylene) and poly (arylene vinylene) represented by poly (2,5-phenylene vinylene), and oligomer materials containing the basic units of these polymers as components, and the constituents of these molecules Deuterated or fluorinated hydrogen can be used.

[0046]

[Table 1]

As a medium for dispersing an organic substance having a non-linear refractive index effect, nitrobenzene, formamide, 1,2-dichloropropane, DMF (dimethylformamide), acetone, chloroform, benzene, Propanol, acetonitrile,
Nitromethane, acrylonitrile, 1,3-propanediol, N, N-dimethylacetamide, acetaldehyde, acetamide, nujol, α-chloronaphthalene, carbon tetrachloride, ethanol, methanol, chlorobenzene, butyl chloride, 1-chloropentane, 1,1 , 2,
2-tetrachloroethane, and these media,
For example, deuterated or fluorinated nitrobenzene or DMF, etc., the cores b0, b1, and b2 produced using these have a refractive index for weak light that does not include the nonlinear refractive index effect. A medium higher than the cladding can be used similarly.

It should be noted that the requirement of χ ⁽³⁾ of the organic substance having a nonlinear refractive index effect to be not less than 10 ⁻¹³ esu is higher than that of a conventional element using quartz glass (SiO ₂ ). In order to reduce the size, the 、 ⁽³⁾ value of quartz glass is 1
This is because it needs to be about one digit larger than 0 ^-14 esu.

The core a1 or a2 may be basically any one as long as the core b1 or b2 has a refractive index equal to or substantially equal to that of the core b1 or b2. For example, GeO ₂
—SiO ₂ , P ₂ O ₅ —SiO ₂ , GeO ₂ —P ₂ O ₅ —Si
O ₂ or SiO ₂ -F as possible out that there the like.

Further, as the clad, the core a1,
As long as it has a smaller refractive index than the core a2 or the core b0, it may be basically any one.
Could be ₂ . The stress applying portion may be basically any material as long as its coefficient of thermal expansion is different from that of the clad.
Can be located in such ₂ -B ₂ O _3.

As the organic dispersion, in addition to a solution in which an organic substance having a nonlinear refractive index effect is dissolved in a liquid medium, a liquid medium containing fine particles of an organic substance having a nonlinear refractive index effect, and a liquid medium having a nonlinear refractive index effect, are used. The refractive index of the core portion for weak light that does not include the nonlinear refractive index effect is larger than that of the cladding portion of the optical fiber, such as a solid medium doped with an organic substance and a solid medium containing fine particles of an organic substance having a nonlinear refractive index effect. If so, it can be used as well.

As a solid dispersion medium for dispersing an organic substance having a nonlinear refractive index effect, polymethyl methacrylate,
Polyacrylate, polystyrene and derivatives thereof, poly (1,1,2,2-tetrafluoropropyl methacrylate), poly (1,1,2,2,3,3,4,4)
4-octafluoropentyl methacrylate) and other fluoroalkyl methacrylate derivative-based homopolymers and copolymers, fluorinated styrene polymers, or fluorinated and deuterated polyalkyl methacrylates, polyalkyl acrylates, polystyrenes such as pentafluoro- A triduterostyrene polymer or a copolymer composed of a combination of these polymers can also be used. In using such a polymer, any substance can be used as long as the substance has a refractive index higher than that of the clad portion of the optical fiber used. In particular, by using a copolymer, fine control of the refractive index is possible.

[0053]

According to the present invention, an organic substance having a non-linear refractive index effect can be uniformly converted into an organic solvent or a polymer material having excellent transparency as compared with a conventional one, for example, an optical fiber in which an organic crystal material is sealed and used as a core. Good optical properties can be obtained for dispersion. That is, when an organic substance having a non-linear refractive index effect is dispersed in an organic solvent or the like, it is extremely easy to make the concentration uniform over the entire range, and therefore, excellent in light transmittance and linear polarization retention of incident light, Further, fine adjustment of the refractive index difference between the core portion and the clad portion of the optical fiber can be achieved uniformly over the entire range.

By using the (1) type nonlinear optical fiber as an optical medium having a nonlinear refractive index effect,
It is possible to realize a compact nonlinear optical device which operates at a low light intensity and is compact.

Further, by using the (2) type nonlinear optical fiber, even when the refractive index of the organic dispersion is non-uniform, the mode pattern of light guided in the fiber is stabilized, and stable operation is achieved. Can be realized.

Further, by using the (3) type nonlinear optical fiber, it is possible to realize an operation which is not affected by disturbance such as fluctuation in core diameter and temperature distribution of the core portion made of the organic dispersion.

The present invention provides an organic substance having a nonlinear refractive index effect in an organic substance dispersion, an organic solvent dispersing the organic substance, or an organic solvent, even when the organic substance dispersion has absorption at the wavelength of signal light or control light. By using deuterated or fluorinated hydrogen constituting these molecules as a high-molecular material, it is possible to realize low-power operation by avoiding absorption and increasing the medium length. FIG. 4 (a) shows a wavelength of 1.0 μm to 1.
It is a result of examining absorption characteristics of nitrobenzene and a deuteride of this solvent at 8 μm. FIG. 4 (a)
Is not practical because nitrobenzene shows a large absorption in the communication wavelength band of 1.3 μm or 1.5 μm, whereas the use of this solvent in deuterated form reduces the absorption in this wavelength band. Indicates that it could be avoided. FIG. 4B shows the absorption characteristics of fluorinated and deuterated hydrogen constituting polystyrene molecules. Polystyrene has a large absorption in the wavelength region of 1 μm or more and is not practical. However, if fluorination is performed, absorption in the communication wavelength region can be escaped, and further deuteration also reduces the absorption. You can see that there is. In addition, benzene also has a large absorption in the communication wavelength region, and it was confirmed that the absorption in this region can be escaped by using fluorinated hexafluorobenzene. Thereby, the chromatic dispersion could be reduced.

From the above, it can be seen that good transmission characteristics can be obtained in an arbitrary wavelength range by using a deuterated or fluorinated organic solvent or the like. By using various organic solvents and the like, or by mixing various organic solvents and the like at an arbitrary ratio, an arbitrary wavelength region (however, 0.6
(μm to 2 μm), of course, good transmission characteristics can be obtained.

As the organic substance having a non-linear refractive index effect, fluorinated or deuterated organic substance is used.
This is for the same reason as described above.

It can be clearly understood from FIG. 5 that the fine adjustment of the refractive index difference between the core and the clad of the optical fiber can be performed. FIG. 5 shows the result of examining the dependency of the refractive index of the solution on the concentration of DEANST when DEANST is dispersed in DMF (the saturation concentration when DMF is used is 40% by weight). For example, a wavelength of 1.06
When it is desired to obtain a refractive index of 1.450 in μm, use this figure to read the solution concentration corresponding to the refractive index of 1.450,
If the solution concentration is 18.4% by weight, the refractive index is exactly 1.
450 is obtained. In addition, if various organic solvents or the like are used, or if various organic solvents or the like are mixed at an arbitrary ratio, it is of course possible to accurately obtain an arbitrary refractive index in a wide range other than that shown here. It is.

When a solid medium is used as the organic dispersion, the response speed is mainly determined by the nonlinear polarization effect.
It has an advantage that it can respond at a higher speed than that due to the molecular orientation effect in a liquid medium.

[0062]

[Embodiment 1] In this embodiment, the result of observing the operation of an optical Kerr shutter switch using the type (1) nonlinear optical fiber of the present invention will be described. DEANST (molecular structure shown in Chemical Formula 1) was used as an organic substance to be sealed in the hollow portion of the glass thin tube.

[0063]

Embedded image

The nonlinear optical fiber has the configuration shown in FIG. In FIG. 6, (a) is a sectional view, (b) is a perspective view, and 61 is a core part having a core diameter D of 125 μm in which a solution obtained by dispersing DEANST in nitrobenzene until saturation (30% by weight) is enclosed. Denotes a glass clad portion having an outer diameter of 1 mm. By controlling the refractive index, n _core >
n _{clad so} that light is efficiently confined in the core. n _core = 1.630, n _clad = 1.50
0, and the relative refractive index difference (n _core −n _clad ) / n _core =
It was set to 8.0%.

FIG. 7 is an experimental system for measuring the characteristics of the optical car shutter switch device 70 of the present invention. Probe light 7
1 is a semiconductor laser light having a wavelength of 0.83 μm, and a gate light is a dye laser light 74 (6 nsec, 1 μm) of the SHG light excitation 73 of the YAG laser 72 having a wavelength of 0.70 μm.
0 Hz). The detector 74 has a response speed of 2n.
sec. Photomar was used. The size of the beam diameter was 110 μm for both the gate light and the probe light. This optical system is a collinear system, and unlike the non-collinear system of the prior art, a longer optical medium, for example, a non-linear optical fiber can be used. It has the feature that high efficiency can be achieved by the conversion.

FIG. 8 shows the gate light intensity Pπ / 6 (light intensity monitored at the output end of the optical fiber and the cell) required to obtain a phase change Δφ = 20 ° (that is, a signal transmittance of 1%). The same applies to the following.) This indicates that the use of the nonlinear optical fiber 80 significantly reduces the required game and light.

When the nonlinear optical fiber 80 is used, since a small spot can be held over a long distance, the medium length L can be obtained from the equation (7) described in the prior art.
Pπ / 6 decreases in inverse proportion to the above, and eventually, in a 100 mm long nonlinear optical fiber, Pπ / 6 is smaller than that in a 1 mm long cell.
6 is 1/75 (since the coupling efficiency of the optical fiber is 66%, if the gate light intensity is monitored at the input end of the optical fiber, 1
/ 50). In the case where the cell 81 is used, I becomes in proportion to L ^-1 from around L = 3 mm due to the beam spread, and immediately saturates. Therefore, the way of decreasing Pπ / 6 is far from that of the fiber. You can clearly see the advantages of using fiber.

Also, DEANST's nitrobenzene 30
With wt% solution, as compared with the case of using only the CS ₂ of the conventional materials it because Ppai / 6 is reduced to 1 / 2.3 (Japanese Patent Application No. 1-14379, an organic nonlinear optical material and Non-linear optical device), after all, the Pπ / 6 value is 2 compared to the conventional CS ₂ optical Kerr shutter switch with 1 mm cell.
This is a significant reduction by more than an order of magnitude.

FIG. 9 shows the gate light intensity P when the medium length is increased by using a 100 mm long nonlinear optical fiber.
The relationship between the _gate (the light intensity monitored at the output end of the optical fiber and the cell; the same applies hereinafter) and the transmittance T are shown.
The T value increases sinusoidally in the low gate light intensity region, but gradually becomes saturated, and when P _gate has a half wavelength intensity,
A maximum transmittance of 27% was obtained. This half-wave intensity P
π was 1.3 kW (2 kW when the gate light intensity is monitored at the input end of the optical fiber because the coupling efficiency of the optical fiber is 66%).

The largest point of this result is only 10
This means that rotation with a phase change amount of π has been achieved with a medium having a length of 0 mm, and this has been realized for the first time in the present invention. The optical fiber of the prior art required a medium length of several hundred meters or more, so that the device could be made much more compact.

In this embodiment, the relative refractive index difference is 8.0.
%, Which is a multimode waveguide, but it is of course possible to change the solvent to 1,2-dichlorobenzene or the like to reduce the relative refractive index difference and achieve a single mode.

Regarding the response speed, it has been reported that the response speed of the conventional optical shutter device made of CS ₂ is 10 ⁻¹² sec.
Also in this example, the response speed was examined. In FIG. 10, a picosecond (10 Hz) Dye laser is used for the gate light, and a streak camera is used for the detector (however, this laser and the streak camera are the same as those in the following experiments of this embodiment and in the ninth and tenth embodiments). Response times using a 3 mm cell each containing CS ₂ ((c) in the figure) and a 15% by weight solution of DEANST in nitrobenzene ((b) in the figure) as an optical medium. Are shown together with the waveform of the gate light ((a) in the figure). From this, CS ₂ is calculated as the value reported conventionally (従 来 2p
sec) and responds at 2.8 psec,
It was experimentally confirmed that the EANST solution also responded at 4 psec, which is about the same as CS ₂ . In CS _2, the response speed is reported to predominantly determined by the orientation effect of the molecule, it is considered to DEANST solution is similar.

Note that this optical car shutter switch has a picosecond switching speed, so that the
Modulation function to apply modulation of 00 GHz or more, 100 GHz
A demultiplexing function that extracts an arbitrary signal pulse from a signal light pulse train having the above repetition frequency and converts it into a low-repetition pulse train, a multiplexing function that multiplexes several low-repetition light pulse trains into an optical pulse train of 100 GHz or more, etc. Can be realized.

[0074]

[Embodiment 2] In this embodiment, a result is shown in which the core diameter D of the type (1) nonlinear optical fiber is made smaller than that in Embodiment 1 and the light density is improved to further increase the efficiency. The optical Kerr shutter device has a core diameter of a nonlinear optical fiber having a length of 100 mm of 30 μm, 20 μm instead of 125 μm.
m, 10 μm, and the beam diameter were also reduced accordingly.

FIG. 11 shows the experimental results. This figure shows the dependence of the signal transmittance characteristic on the gate light intensity P _gate (the light intensity monitored at the output end of the optical fiber; the same applies hereinafter). In a region where the gate light intensity is as small as this, when the core diameter is 125 μm, the amount of phase change is extremely small, and therefore, the obtained transmittance is also very small. The phase change amount π is obtained even with such a small gate light intensity. 1/2 of gate light intensity
The wavelength intensity Pπ decreases as the core diameter decreases to 30, 20, and 10 μm.
(Since the coupling efficiency of the optical fiber is 24%, the gate light intensity is 50 W when monitored at the incident end of the optical fiber.) As a result, the gate light intensity was reduced by more than two orders of magnitude as compared with the case where the core diameter was 125 μm. In addition, as shown in the figure, the signal transmittance gradually decreases as the core diameter decreases, and T = 5% at 10 μm. This is because the inside of the core is spatially non-uniform. Can be Also in this embodiment, the relative refractive index difference is 8.0.
%, The multi-mode waveguide had a nearly 100 mode number even with a fiber having a core diameter of 10 μm.

FIG. 12 is a graph plotting the relationship between Pπ and 1 / D in order to examine the advantages of reducing the core diameter in more detail. When the core diameter becomes smaller,
The required gate light intensity Pπ is greatly reduced substantially in proportion to D ^-2 . That is, the gate light intensity is reduced in proportion to the core area in the region examined in the present embodiment, and it is very effective to reduce the core diameter to increase the efficiency, that is, to reduce the gate light intensity. Recognize.

[0077] Then, when combined with the results of Example 1, an optical Kerr shutter switch is a nonlinear optical device of the present invention, as compared to that using conventional 1mm cell CS _2,
This means that the gate light intensity can be reduced by as much as four digits.

Similar results were obtained by using another material as the organic dispersion dispersed in the hollow portion of the glass thin tube of the type (1) nonlinear optical fiber of the present invention. For example, DM
When the operation of the optical Kerr shutter switch was examined using a solution in which SM (the molecular structure is shown in Chemical Formula 2) was dissolved in formamide until it was saturated (20% by weight), the same high efficiency as in the DEANST solution was achieved. That is, the core diameter is 10 μm
When a fiber having a length of 100 mm was used, the required gate light intensity could be reduced to 15 W (60 W when monitored at the input end of the optical fiber).

[0079]

Embedded image

Further, in the type (1) nonlinear optical fiber of the present invention, by further increasing its length, higher efficiency is achieved, and a switch operation becomes possible even when a semiconductor laser is used as the gate light. Was. That is, when the switch operation was examined with a fiber length of 1 m, a signal transmittance of 1% was obtained (described below).
Similar results were obtained using (2) and (3) type nonlinear optical fibers). The result that the switching operation was observed even when the semiconductor laser was used as the gate light was realized for the first time by the present invention.

[0081]

Embodiment 3 In this embodiment, a method of manufacturing a (2) nonlinear optical fiber and its characteristics will be described.

FIG. 13 is a cross-sectional view of the type (2) nonlinear optical fiber of the present invention. Here, the core a131 is SiO ₂ having a diameter of 6 μm and GeO ₂ added to about 7 mol%.
The glass and the core b132 are those in which a solution of 20% by weight of DEANST dispersed in 1,2-dichloropropane is sealed in the hollow part of the core a131 having a diameter of 5 μm, and the cladding 133 is pure SiO ₂ glass. The 1,2-dichloropropane solution was used at the wavelengths used in the following examples (up to 1.
(3 .mu.m band), which has extremely good transmission characteristics. The fiber outer diameter was 200 μm. Core a131 and core b1
The refractive index for the weak light of 32 was about 1.456 at a wavelength of 1.32 μm, and the relative refractive index difference between the cores a and b and the clad was 0.62%.

In the manufacturing method of this embodiment, a drawing as shown is performed using a base material having a structure as shown in FIG. That is, the hole 1 for inserting the core base material 142 into the cladding base material 141 by ultrasonic drilling.
43 is opened and polished to a predetermined size. Similarly, a hole 146 for enclosing the organic dispersion is formed in the core base material by ultrasonic drilling, and is polished to a predetermined size. Then, the core base material 142 is inserted into the hole of the cladding base material, heated to about 2000 ° C. by the heater 147, drawn in the direction of the arrow, and processed into a fiber shape. Then, the organic dispersion is sealed in a hollow portion at the center of the fiber thus formed.

In the above embodiment, 1,2-dichloropropane solution of DEANST is used as the material of the core b132 having a nonlinear optical effect, and GeO ₂ is used as the material of the core a131.
Although but with SiO ₂ glass which is added, the addition, equal to both the core a131 and the core b132 the refractive index of the high core a131 and the core b132 refractive index with respect to the weak light than the material used for the cladding 133 Any combination can be used as long as it is a combination capable of confining the incident light and the material of the core b132 has a large nonlinear optical effect. In this embodiment, the cores a131 and b
Although the refractive index difference between 132 and the cladding was 0.62%,
Even when this value was increased to 1%, the mode pattern was sufficiently stable.

As described above, according to the present invention, the core b13
An organic dispersion having a large nonlinear optical effect is used for 2 and glass is used for the core a131.
By adjusting the materials to make them equal, the core a1
By confining the light in 31 and the core b132, the light is efficiently confined in the core b132 and guided stably,
A nonlinear optical fiber having a large nonlinear optical effect can be obtained.

[0086]

Embodiment 4 In this embodiment, a method of manufacturing a (3) type nonlinear optical fiber and its characteristics will be described.

FIG. 15 is a cross-sectional view of the type (3) nonlinear optical fiber of the present invention. Here the core A 151 SiO ₂ is the added GeO ₂ is about 7 mol% in diameter 6μm
The glass, the core b152, was prepared by enclosing a solution in which 20% by weight of DEANST was dispersed in 1,2-dichloropropane in a hollow part having a diameter of 5 μm of the core a151, the cladding 153 was pure SiO ₂ glass, and the stress applying part 154 was the diameter. 40μ
m ₂ is SiO ₂ glass to which about 15 mol% of B ₂ O ₃ is added. The fiber outer diameter was 200 μm, and the distance between the centers of the stress applying portions was 76 μm. Core a 151, clad 15
3 and the thermal expansion coefficient of the stress applying portion 154 are 7
× 10 ^-7 ° C ^-1 and 25 × 10 ^-7 ° C ^-1 and the core a15
1 and the core b152 have a refractive index of 1.3 for weak light.
At 2 μm, both were about 1.456, core a151,
The relative refractive index difference between b152 and the cladding was 0.62%. The mode pattern was sufficiently stable even when the relative refractive index difference between the cores a151 and b152 and the clad was increased to 1%. Note that the relative refractive index difference between the stress applying section and the cladding may be 0 or a negative value so that light is not guided to the stress applying section.

In the manufacturing method of this embodiment, a drawing as shown is performed using a base material having a structure as shown in FIG. That is, one hole 163 for inserting the core base material 162 and two holes 165 for inserting the stress applying part base material 164 are formed in the cladding base material 161 by ultrasonic drilling. And polished to predetermined dimensions. Similarly, a hole 166 for enclosing the organic material dispersion is formed in the core base material by ultrasonic drilling, and is polished to a predetermined size. Each of the core base material 162 and the stress applying portion base material 164 is inserted into a hole of the cladding base material, heated to about 2000 ° C. by a heater 167, and drawn in the direction of an arrow to be processed into a fiber shape. Then, the organic dispersion is sealed in a hollow portion at the center of the fiber thus formed.

FIG. 17 shows a stress distribution in a cross section in this embodiment. In this embodiment, since the coefficient of thermal expansion of the stress applying portion 154 is larger than that of the cladding 153, the core a in the cross section of the fiber as shown in FIG.
A large tension remains in the x-axis direction inside 151 and around the core a151. Here, assuming that the stresses in the x and y axis directions in the core are σ ^x and σ ^y , two fundamental modes HE ₁₁
^x and HE ₁₁ ^y mode respectively the effective refractive indices n ^x and n ^y are the,

[0090] _{^{n x = β x / k =}} n x + C 1 σ x + C 2 σ y (1)

[0091] _{^{n y = β y / k =}} n y + C 2 σ x + C 1 σ y (2)

[0092] B = nx-ny = (β x -β y) / k = (n x0 -n y0) + (C 1 -C 2) (σ x -σ y) (3)

Is obtained. Where β _x and β _y are HE
₁₁ ^x and HE ₁₁ ^y mode propagation constants, where k is the wave number C
₁ and C ₂ are photoelastic constants, _nx0 and _ny0 are effective refractive indexes when no stress is applied, respectively, and _nx0 = _ny0 when the core is circular.

B is a birefringence index. If this birefringence index is increased, coupling between the two fundamental modes becomes difficult to occur. Therefore, even if there is disturbance such as bending of the fiber or temperature fluctuation, incident linearly polarized light is present. Can be held over long distances. In this embodiment, B is about 3 × 10 ⁻⁴ .

In the above embodiment, 1,2-dichloropropane solution of DEANST is used as the material of the core b152 having a nonlinear optical effect, and GeO ₂ is used as the material of the core a151.
Although but with SiO ₂ glass which is added, the addition, to equally both the core a151 and the core b152 the refractive index of the high core a151 and the core b152 refractive index with respect to the weak light than the material used for the cladding Any combination that can confine incident light and the material of the core b152 having a large nonlinear optical effect can be used in the same manner.

As described above, according to the present invention, the core b15
2, an organic dispersion having a large nonlinear optical effect is used, and glass is used for the core a151.
By adjusting the material to make it equal, the core b1
By confining the light to the core 52 and the core a 151 and further giving the core b 152 a birefringence index by the stress applying part,
It is possible to obtain a polarization-maintaining nonlinear optical fiber that has a large nonlinear optical effect and maintains incident linear polarization over a long distance.

[0097]

Fifth Embodiment In this embodiment, in an optical Kerr shutter switch, the (1) type nonlinear optical fiber is the (2) type (and (3) type) nonlinear optical fiber shown in the third embodiment (and the fourth embodiment). Instead of this, even when the refractive index of the organic dispersion has non-uniformity, the results show that the mode pattern of light guided in the fiber is stabilized and stable operation is realized. The optical Kerr shutter switch device has changed the nonlinear optical fiber,
The probe light is a semiconductor laser having a wavelength of 1.28 μm, and the gate light is Nd: mode lock YA having a wavelength of 1.32 μm.
This is the same as the first embodiment except that the G laser pulse is used. The (2) type nonlinear optical fiber used was the one shown in Example 3, and the relative refractive index difference between the core a131, the core b132 and the clad was 0.62%. The mode pattern was sufficiently stable even when this value was increased to 1%.

In this embodiment, the required gate light intensity was greatly reduced as in the second embodiment. However, the most important point of the present invention is that the refractive indexes of the core b 132 and the core a 131 are adjusted. The core a131
And confining the light in the core b132,
The light is efficiently confined in the 12 portions and guided stably, and as a result, the obtained switching operation is extremely stable.

The advantage of the type (2) nonlinear optical fiber of the present invention can be taken advantage of when the power is further reduced by increasing the length of the medium. When a long medium length is used, it is difficult for the type (1) nonlinear optical fiber to maintain the refractive index difference between the core and the cladding in the fiber, and the mode pattern in the nonlinear optical fiber becomes unstable. As a result, there may be a case where a stable operation cannot be obtained. In such a case, the core a131 and the core b1
By using a double-core optical fiber having a structure to confine light in both of them, it is possible to stabilize the mode pattern of light guided in the fiber even if the refractive index of the organic dispersion is non-uniform. , Stable operation can be realized.

When a longer medium length is used, the polarization state in the nonlinear optical fiber becomes unstable if there is disturbance such as fluctuation of the core diameter of the core portion or temperature distribution. Uses the interference effect, the operation may be unstable. In such a case, a stable element operation can be obtained by using the type (3) nonlinear optical fiber (however, since the characteristics of elliptical polarization may be unstable, book of
(3) Type nonlinear optical fiber
° Joined at an angle and solved by using this). A core a151 having a refractive index substantially equal to that of the core b152 made of the organic dispersion in the nonlinear optical fiber is newly provided outside the core b152 made of the organic dispersion to confine light in both the core a151 and the core b152. In addition, by providing the stress applying portion 154 in the clad, a stress caused by a difference in thermal expansion coefficient between the clad 153 and the stress applying portion is applied to the core a151, and the stress induced birefringence of the core a151 is used in the fiber. This is because, by using a nonlinear optical fiber that maintains the polarization in the above, the polarization state in the nonlinear optical fiber can be stabilized, and extremely stable operation can be realized without being affected by disturbance or the like.

[0101]

[Embodiment 6] In this embodiment, results of observation of the operation of a fiber loop mirror switch using the type (1) nonlinear optical fiber of the present invention will be described.

FIG. 18 is a diagram showing an embodiment of the present invention.
Here, 181 is a signal light having a wavelength of 1.28 μm, 182 is a control light pulse having a width of 2 ps obtained by pulse compression of an Nd: mode-locked YAG laser having a wavelength of 1.32 μm,
183 is a PANDA fiber coupler that combines the signal light and the control light, and 184 is a PAND that splits the signal light and the control light.
A fiber coupler 185 has almost 50
%, PANDA with almost 0% branching ratio for control light
The fiber coupler 186 is made of SiO ₂ shown in FIG.
187 is a (1) type nonlinear optical fiber produced by enclosing a solution in which DEANST is dispersed in 1,2-dichloropropane at 20% by weight in a hollow portion 192 having an inner diameter of 5 μm of a hollow small-diameter tube having a length of 10 cm made of Demultiplexed outgoing signal light, 18
8 is a signal light switched by the control light, 189
183a is a signal light input end, 183b is a control light input end, 184a is a signal light output end, and 184b is a control light output end. The (1) type nonlinear optical fiber used in this embodiment has an outer diameter of 125 μm,
The refractive index of the core made of the 1,2-dichloropropane solution of ST was 1.546 at a wavelength of 1.32 μm, and the relative refractive index difference between the core and the clad was 0.62%.

As shown in FIG. 18, the control light incident end 1
When the control light is not incident on the signal light incident end 18 b
The signal light incident from 3a is a (1) type nonlinear optical fiber 1
The light returns to the signal light incident end 183a by an interferometer composed of the 86 and the PANDA fiber coupler 185. On the other hand, when the control light pulse is incident on the control light incident end 183b, of the signal light equally divided by the PANDA fiber coupler 185, the signal light traveling in the same direction as the control light pulse in the (1) type nonlinear optical fiber. Undergoes phase modulation due to the nonlinear refractive index effect, the PANDA fiber coupler 1
The signal light is finally emitted to the signal light emitting end 184a by the interference effect at 85.

FIG. 20 shows a control light pulse waveform and a signal light emitting end 184 when a continuous light is input as a signal light and an optical pulse having a width of 2 ps is input as a control light to the optical control optical switch of this embodiment.
The waveform of the emitted signal light pulse is shown in FIG. According to this embodiment, if the intensity of the control light pulse has a peak value of 10 W, 100% of the signal light can be switched to the signal light emitting end 184a. Also in this embodiment, since it has a switching speed of 10 ps or less as apparent from FIG.
Modulation function for modulating signal light at 100 GHz or higher, 1
A demultiplexing function for extracting an arbitrary signal pulse from a signal light pulse train having a repetition frequency of 00 GHz or more and converting the signal pulse into a low-repetition pulse train, a demultiplexing function for converting the signal pulse into a low-repetition pulse train, and the like can be realized. . A multiplexing function for multiplexing several low repetition optical pulse trains into an optical pulse train of 100 GHz or more can be realized. In the present embodiment, according to the present invention, it is possible to use a nonlinear optical fiber using DEANST as a medium having a nonlinear optical effect. The device can be configured.

In the above embodiment, 1,2-dichloropropane solution of DEANST was used as the material of the core b having the nonlinear optical effect, and SiO ₂ was used for the clad.
In addition, the same combination can be used as long as the combination has a higher refractive index for weak light than the material used for the cladding and the material of the core b has a nonlinear optical effect.

In this embodiment, the medium length is 10 cm.
Further power reduction can be achieved by increasing the medium length. However, when such a long medium length is used, it is difficult to maintain the refractive index difference between the core and the cladding in the nonlinear optical fiber, and the mode pattern in the nonlinear optical fiber becomes unstable, and as a result, There may be cases where stable operation cannot be obtained. In such a case, as shown in FIG. 13, a (2) type nonlinear optical fiber, that is, a core b composed of an organic substance dispersion in the nonlinear optical fiber
A core a131 having a refractive index substantially equal to 132 is newly provided outside the core b made of an organic dispersion to form a core a13.
1 having a structure to confine light in both 1 and core b132
By using the heavy-core type optical fiber, even when the refractive index of the organic dispersion is non-uniform, the mode pattern of the light guided in the fiber can be stabilized, and a stable operation can be realized.

When a longer medium length is used, if there is disturbance such as fluctuation in core diameter or temperature distribution in the core portion, the polarization state in the nonlinear optical fiber becomes unstable. Uses the interference effect, the operation may be unstable. In such a case, as shown in FIG. 15, a (3) type nonlinear optical fiber, that is, a core a151 having a refractive index substantially equal to that of the core b152 made of an organic dispersion in the nonlinear optical fiber.
Is newly provided outside the core b 151 made of an organic material dispersion, light is confined in both the core a and the core b, and the stress applying part 154 is provided in the clad, so that the clad 153 and the stress applying part The stress caused by the difference in the thermal expansion coefficient is applied to the core a, and the nonlinear optical fiber that maintains the polarization in the fiber by using the stress-induced birefringence of the core a is used. The polarization state is stabilized, and an extremely stable operation can be realized without being affected by disturbance or the like.

[0108]

Seventh Embodiment FIG. 21 is a view showing an embodiment of a Mach-Zehnder type optical control optical switch to which the (2) type nonlinear optical fiber shown in FIG. 13 of the third embodiment is applied. Here, the signal light source 211 is a semiconductor laser having a wavelength of 1.30 μm,
Reference numeral 12 denotes a YAG laser having a wavelength of 1.32 μm, and light from each light source is PAND using lenses 213 and 214.
Incident ends 215a, 215b of A fiber coupler 215
Respectively. PANDA fiber coupler 2
Reference numeral 15 denotes a signal light having a wavelength of 1.30 μm,
The light is branched at 15:50 at 50:50, and the excitation light having a wavelength of 1.32 μm is branched only to the emission end 215c. Further, the output ends 215c and 215d of the fiber coupler 215 are
The (2) type nonlinear optical fiber 216 and the silica-based PANDA fiber 217 are optically connected to each other.
Input ends 218a, 218 of NDA fiber coupler 218
8b. The PANDA fiber coupler 218 outputs signal light having a wavelength of 1.30 μm to the emission end 21.
8c, 218d, 50:50, 1.32μ wavelength
The m excitation light is branched only to the emission end 218d.

When there is no pump light, all of the signal light is emitted from the output end 218 of the PANDA fiber coupler 218.
d. However, when the pump light is incident, the signal light passing through the nonlinear optical fiber 216 undergoes phase modulation due to the nonlinear refractive index effect. The relationship between the intensity P of the pump light and the phase change amount δφ received by the signal light passing through the nonlinear optical fiber 216 is expressed by the following equation.

Δφ = 2πL (2n ₂ ) P / A _eff.

Here, L is the fiber length, n ₂ is the nonlinear refractive index, and A _eff. Is the effective core area. At this time, the intensity I _{c of the} signal light emitted to the emission ends 218c and 218d,
I _d is represented by the following equations.

I _c = (1−cos δφ) / 2

I _d = (1 + cosδφ) / 2

As can be seen from this equation, the intensity of the signal light emitted to the emission ends 218c and 218d can be controlled by the intensity of the excitation light. Here, since the excitation light is also emitted from the emission end of 218d, the signal light emitted from the emission end 218d needs to be separated from the excitation light by the PANDA fiber coupler for demultiplexing.

In this embodiment, the length of 10 m shown in FIG.
Using a (2) type nonlinear optical fiber, I _c = 0.02 and I _d = 0.98 were obtained when the peak power of the pump light was 400 mW. FIG. 22 shows continuous light as signal light and width 1 as excitation light.
The waveform of the signal light obtained from the emission ends 218c and 218d when a mode-locked pulse of 00 ps is incident is shown.
The signal light incident as continuous light follows the waveform of the excitation light modulated by the excitation light pulse. Since the DEANST solution responds in picoseconds as shown in the first embodiment, the present embodiment can control the signal light by using an excitation light pulse shorter than 100 ps shown here. Further, in the present embodiment, the present invention enables the entire device to maintain the polarization of the signal light and the excitation light, so that extremely stable operation can be realized without being affected by disturbance or the like.

In this embodiment, according to the present invention, it is possible to use a nonlinear optical fiber using DEANST as a medium having a nonlinear optical effect. , A compact device can be constructed.

Further, in the above embodiment, 1,2-dichloropropane solution of DEANST was used as the material for the core having the nonlinear optical effect, and SiO ₂ was used for the clad. However, the light was weaker than the material used for the clad. Any combination of materials having a high refractive index with respect to and having a core material having a nonlinear optical effect can be used.

[0118]

Eighth Embodiment FIG. 23 is a view showing an embodiment of an optical switch to which the (3) type nonlinear optical fiber shown in FIG. 15 of the fourth embodiment is applied. Here, the signal light source 231 is a semiconductor laser with a wavelength of 1.30 μm, and the excitation light source 232 is Y with a wavelength of 1.32 μm.
An AG laser, and the light of each light source is
PANDA fiber coupler 235 using
Are incident on the incident ends 235a and 235b, respectively.

The PANDA fiber coupler 235 transmits the signal light having a wavelength of 1.30 μm to the emission ends 235c and 235d.
At 0:50, the pump light having a wavelength of 1.32 μm is branched only to the emission end 235c. Furthermore, fiber coupler 2
The exit ends 235c and 235d of the 35 are the (2) type nonlinear optical fiber 236 of the present invention and the silica-based PANDA fiber 23.
7 are optically connected to each other with their polarization maintaining axes aligned. The nonlinear optical fiber 236 and the PANDA fiber 7 are connected to the entrance end 238 of a PANDA fiber coupler 238.
a and 238b are connected so that the axes of polarization maintenance are aligned. The PANDA fiber coupler 238 transmits the signal light having a wavelength of 1.30 μm to the emission ends 238c and 238d.
At 0:50, the pump light having a wavelength of 1.32 μm is branched only to the emission end 238d.

When there is no pump light, all of the signal light is emitted from the output end 238 of the PANDA fiber coupler 238.
d. However, when the excitation light is incident, the polarization maintaining (3) type nonlinear optical fiber 2
The signal light passing through 36 undergoes phase modulation. The relationship between the intensity P of the pump light and the amount of phase change δφ received by the signal light passing through the polarization-maintaining nonlinear optical fiber 236 is expressed by the following equation.

Δφ = 2πL (2n ₂ ) P / A _eff.

Here, L is the fiber length, n ₂ is the nonlinear refractive index, and A _eff. Is the effective core area. At this time, the intensity I _{c of the} signal light emitted to the emission ends 238c and 238d,
I _d is represented by the following equations.

I _c = (1−cos δφ) / 2

I _d = (1 + cos δφ) / 2

As can be seen from this equation, the intensity of the signal light emitted to the emission ends 238c and 238d can be controlled by the intensity of the excitation light. Here, since the excitation light is also emitted from the emission end of 238d, the signal light emitted from the emission end 238d needs to be separated from the excitation light by the PANDA fiber coupler for demultiplexing.

In this embodiment, the length of 10 m shown in FIG.
(3) type using a nonlinear optical fiber polarization maintaining the peak power of the excitation light is I _c = 0.02 in 400 mW, I _d = 0.9
8 was obtained. FIG. 24 shows waveforms of the signal light obtained from the output ends 238c and 238d when a continuous light is input as the signal light and a mode-locked pulse having a width of 100 ps is input as the excitation light. The signal light incident as continuous light follows the waveform of the excitation light modulated by the excitation light pulse. DEANS
Since the T solution responds in picoseconds as shown in the first embodiment, in the present embodiment, it is possible to control the signal light by using an excitation light pulse shorter than 100 ps shown here. Further, in the present embodiment, the present invention makes it possible for the entire device to maintain the polarization of the signal light and the excitation light,
Extremely stable operation can be realized without being affected by disturbance or the like.

In the present embodiment, a nonlinear optical fiber using DEANST can be used as a medium having a nonlinear optical effect according to the present invention. , A compact device can be constructed.

Further, in the above embodiment, 1,2-dichloropropane solution of DEANST was used as the material of the core having the nonlinear optical effect, and SiO ₂ was used for the cladding. Any combination of materials having a high refractive index with respect to and having a core material having a nonlinear optical effect can be used.

[0129]

Embodiment 9 In this embodiment, in an optical Kerr shutter switch, a solid-state medium is used as an organic dispersion to be sealed in a hollow portion of a (1) type nonlinear optical fiber, and a liquid-like medium is used. This shows the results of not only making the device compact, but also realizing faster response by taking advantage of the solid-state medium.

As an organic substance having a nonlinear refractive index effect,
SBA (molecular structure is shown in Chemical formula 3) was used, and this was dispersed in polymethyl methacrylate to obtain a solid medium. The dispersion concentration is 5% by weight. The optical Kerr shutter switch device is different from the (1) type nonlinear optical fiber in that the medium to be filled in the hollow portion is different, the core diameter of the optical fiber is 10 μm, and the fiber length is 100 mm.
This is similar to the first embodiment.

[0131]

Embedded image

In this embodiment, as in the first embodiment, the relationship between the gate light intensity P _gate (the value monitored at the exit end of the optical fiber) and the transmittance T was examined. The T value increases sinusoidally in the low gate light region, but gradually saturates,
It was confirmed that the maximum transmittance was obtained in the same manner as in Example 1 when the _gate had a 波長 wavelength intensity. The Pπ value at the half wavelength intensity was 20 W.

Also, in this example, the response speed was examined almost in the same manner as in Example 1, and it was experimentally confirmed that the response speed was faster than picoseconds. This is because in a device using a fiber filled with a liquid medium, the response speed of the material is determined by the molecular orientation effect. In the device using, the response speed of the material is faster (<10 ^-14 s).
ec) This is due to the fact that the response speed of the device has been increased in accordance with the nonlinear polarization effect.

That is, according to the present invention, not only can the device be operated at lower power than the conventional device,
This means that an optical car shutter switch capable of high-speed response has been realized.

[0135]

Embodiment 10 In this embodiment, in an optical Kerr shutter switch, an organic substance having a larger nonlinear refractive index effect than in Embodiment 9 is dispersed as a nonlinear refractive index medium to be sealed in the hollow portion of the type (1) nonlinear optical fiber. The results show that the response speed was increased and the efficiency was further increased by using a solid medium.

As an organic substance having a nonlinear refractive index effect,
SBAC (molecular structure shown in Chemical Formula 4) was used, and this was dispersed in polymethyl methacrylate to obtain a solid medium. The dispersion concentration is 5% by weight. The optical Kerr shutter switch device is the same as that of the ninth embodiment except that the medium enclosed in the hollow portion of the (1) type nonlinear optical fiber is different.

[0137]

Embedded image

In the present embodiment, the use of an organic substance having a larger nonlinear optical effect than in Embodiment 9 corresponds to 1 /
The Pπ value at a two-wavelength intensity was 15 W (the value monitored at the output end of the optical fiber), which was lower than that in Example 9. Regarding the response speed, it was experimentally confirmed that the response speed of the device was faster than the picosecond.

[0139]

As described above, the present invention has the following effects.

(1) The non-linear optical fiber of the present invention obtains better optical characteristics by dispersing the material more uniformly than a conventional one, for example, a single crystal material is encapsulated and used as a core. be able to. That is, when an organic substance having a non-linear refractive index effect is dispersed in an organic solvent or the like, it is extremely easy to make the concentration uniform over the entire range, and therefore, excellent in light transmittance and linear polarization retention of incident light,
Further, fine adjustment of the refractive index difference between the core portion and the clad portion of the optical fiber can be achieved uniformly over the entire range.

(2) Since the non-linear optical fiber of the present invention encapsulates an organic material having a high response speed and a large non-linear refractive index effect, it can exhibit a large non-linear optical effect, and is therefore more compact than ever. in spite of,
It is possible to realize an all-optical switch that can operate with low optical power and has a high operation speed. In addition, by using a double-core nonlinear optical fiber, better refractive index control can be obtained, so that the medium length can be increased and the operating power can be further reduced. Then, by using the stress applying type nonlinear optical fiber, it is possible to realize an all-optical switch which is extremely stable against disturbances and the like.

(3) The nonlinear optical device of the present invention has a 10p
Since a switch that operates at a very high speed of s or less can be realized, there is an advantage that large-capacity optical data / information processing and optical communication of 100 GHz or more can be performed. In addition, since high efficiency is achieved, there is an advantage that a switch operation can be realized even when a semiconductor laser is used as gate light by using a nonlinear optical fiber having a long medium length.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional optical car shutter switch.

FIG. 2 is a configuration diagram of a conventional fiber loop mirror switch.

FIG. 3 is a configuration diagram of a conventional lithium niobate Mach-Zehnder switch.

FIG. 4a shows the characteristics of the deuteration of nitrobenzene.

FIG. 4b shows the characteristics of fluorination and deuteration of polystyrene.

FIG. 5 is a graph showing the dependency of the refractive index of a solution in which DEANST is dispersed in DMF on the concentration of DEANST.

FIG. 6a is a sectional view of a (1) type nonlinear optical fiber used in the first and second embodiments.

FIG. 6B is a perspective view of a (1) type nonlinear optical fiber used in the first and second embodiments.

FIG. 7 is a configuration diagram of an optical car shutter switch of the present invention.

FIG. 8 is a diagram showing a medium length dependency of a gate light intensity P ₀ required to obtain a phase change amount Δφ = 20 °.

FIG. 9 is a diagram showing a relationship between a signal transmittance T and a gate light intensity P _gate .

FIG. 10A is a diagram showing a waveform of a gate light.

FIG. 10B is a diagram showing the result of observing the response speed of DEANST.

FIG. 10C is a diagram showing the results of observing the response speed of CS ₂ .

FIG. 11 is a diagram showing the dependence of signal transmittance characteristics on gate light intensity.

FIG. 12 is a diagram showing a relationship between Pπ and 1 / D.

FIG. 13 is a cross-sectional view of the type (2) nonlinear optical fiber.

FIG. 14 is a diagram showing a method for manufacturing a type (2) nonlinear optical fiber.

FIG. 15 is a cross-sectional view of the type (3) nonlinear optical fiber.

FIG. 16 is a diagram showing a method for producing a (3) -type nonlinear optical fiber.

FIG. 17 is a sectional stress distribution diagram of the (3) type nonlinear optical fiber.

FIG. 18 is a configuration diagram of a fiber loop mirror switch of the present invention.

FIG. 19a is a sectional view of a (1) type nonlinear optical fiber used in Example 6.

FIG. 19a is a perspective view of a (1) type nonlinear optical fiber used in Example 6.

FIG. 20 is a diagram illustrating input / output characteristics of the loop mirror switch according to the sixth embodiment.

FIG. 21 is a configuration diagram of a Mach-Zehnder switch according to a seventh embodiment of the present invention.

FIG. 22 is a diagram showing input / output characteristics of the Mach-Zehnder switch according to the present invention of Example 7.

FIG. 23 is a configuration diagram of a Mach-Zehnder switch according to an eighth embodiment of the present invention.

FIG. 24 is a diagram showing input / output characteristics of the Mach-Zehnder switch according to the eighth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Nonlinear refractive index medium 12a, b Polarizer 21 Signal light 22 Control light 23 Optical coupler 24 Optical fiber 25 Emitted signal light when control light is not incident 26 Emitted signal light when control light is incident 31 Core 32 Niobic acid Lithium substrate 33 Electrode 61 Core filled with nitrobenzene saturated solution of DEANST 62 Cladding part of glass 70 Optical car shutter switch device 71 Probe light 72 YAG laser 73 Dye laser 74 Detector 80 (1) type nonlinear optical fiber 81 Cell 131 GeO ₂ A 132 made of SiO ₂ to which is added a core b 132 made of DEANST / 1,2-dichloropropane solution clad made of SiO ₂ 141 base material for clad 142 base material for core 143 hole for core 146 hole for core b 147 heater 151 GeO ₂ is added Core a 152 DEANST / 1,2- a core b 153 SiO ₂ consisting dichloropropane solution cladding 154 stress applying section 161 Koraddo preform 162 for the core preform 164 stress applying section preform 165 made of SiO ₂ that was Hole for stress applying part 166 Hole for core b 167 Heater 181 Signal light 182 Control light 183 First PANDA fiber coupler 184 Second PANDA fiber coupler 185 Third PANDA fiber coupler 186 (1) type nonlinear optical fiber 187 Emission control Light 188 Switched outgoing signal light 189 Unswitched outgoing signal light 183a Signal incident light 183b Control light incident end 184a Signal light emitting end 184b Control light emitting end 191 Cladding made of hollow small-diameter tube of SiO ₂ 192 DEANST / 1,2 -Core made of dichloropropane solution 211 signal light source 212 excitation light source 213 lens 214 lens 215 first PANDA fiber coupler 216 type (2) nonlinear optical fiber 217 PANDA fiber 218 second PANDA fiber coupler 215a first PANDA Input end of fiber coupler 215b Input end of first PANDA fiber coupler 215c Output end of first PANDA fiber coupler 215d Output end of first PANDA fiber coupler 218a Input end of second PANDA fiber coupler 218b Second PANDA SiO ₂ exit end 231 GeO ₂ exit end 218d second PANDA fiber coupler of the entrance end 218c second PANDA fiber coupler fiber coupler is added Tona Core a 232 DEANST / 1,2- consisting dichloropropane solution cores b2 233 made of SiO ₂ cladding 211 signal source 212 excitation light source 213 lens 214 lens 215 of the first PANDA fiber coupler 216 invention (3) nonlinear optical fiber 217 PANDA fiber 218 Second PANDA fiber coupler 215a Input end of first PANDA fiber coupler 215b Input end of first PANDA fiber coupler 215c Output end of first PANDA fiber coupler 215d Output end of first PANDA fiber coupler 218a Input end of second PANDA fiber coupler 218b Input end of second PANDA fiber coupler 218c Output end of second PANDA fiber coupler 218d Second PAN Emitting end of A fiber coupler

Continued on the front page (31) Priority claim number Japanese Patent Application No. 2-417494 (32) Priority date Hei 2 (1990) December 28 (33) Priority claim country Japan (JP) Preliminary examination (72) Inventor Hideki Kobayashi 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Hiroki Ito 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Shoichi Sudo Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo (72) Inventor Takashi Kurihara, 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Naoki Ohba, Inventor Tokyo Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwai-cho, Chiyoda-ku (72) Inventor Toshikuni Kaino 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A 62-15713 (JP, A) JP-A-63-227665 (JP, A) JP-A-2-193126 (JP, A) JP-A-60-2374 25 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G02F 1/35 G02F 1/35 504

Claims (23)

(57) [Claims] An organic substance dispersion in which an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency, and the refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion. Has a refractive index equal to that of the organic substance dispersion, which is mainly composed of glass and has a hollow portion for enclosing the organic substance dispersion in a non-linear optical fiber enclosed in a hollow small-diameter tube mainly composed of glass. Structure having a core a1, a core b1 made of the organic dispersion sealed in the center of the core a1, and a clad disposed outside the core a1 and mainly composed of glass and having a smaller refractive index than the core a1. A nonlinear optical fiber characterized by the above-mentioned. 2. The organic material having a nonlinear refractive index effect is 3
The following nonlinear susceptibility χ ⁽³⁾ is 1 × 10 ⁻¹³ esu
The nonlinear optical fiber according to claim 1, wherein: 3. The organic substance having the nonlinear refractive index effect,
Either a molecular crystalline material, or an ionic crystalline material, or an π-electron conjugated oligomer or polymer material, or an organic dispersion in which a combination thereof is dispersed in an organic solvent or a polymer material having excellent transparency, or 3. The nonlinear optical fiber according to claim 1, wherein the nonlinear optical fiber is a combination of these. 4. The method according to claim 1, wherein the organic substance and the organic solvent in which the organic substance is dispersed or the polymer material having excellent transparency are obtained by deuterating or fluorinating hydrogen constituting the molecules. The nonlinear optical fiber according to any one of claims 1 to 3. 5. The material of the core a1 is GeO ₂ —SiO ₂ ,
P ₂ O ₅ —SiO ₂ , GeO ₂ —P ₂ O ₅ —SiO ₂ or SiO ₂ —F, and the material of each of the claddings is Si
One of nonlinear optical fiber according to claim 4, wherein the claim 1, characterized in that the O _2. 6. An organic substance dispersion in which an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency, and the refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion. Has a refractive index equal to that of the organic substance dispersion, which is mainly composed of glass and has a hollow portion for enclosing the organic substance dispersion in a non-linear optical fiber enclosed in a hollow small-diameter tube mainly composed of glass. A core a2, a core b2 composed of the organic dispersion dispersed in the center of the core a2, a clad disposed outside the core a2 and mainly composed of glass and having a smaller refractive index than the core a2, Having at least two stress applying portions mainly composed of glass disposed therein,
The stress applying portion is opposed to the core a2 and separated from the core a2, and the thermal expansion coefficient of the stress applying portion is different from the thermal expansion coefficient of the clad, and the non-axially symmetric stress A polarization-maintaining nonlinear optical fiber having a stress imparting type, characterized by a structure in which a stress is applied. 7. The organic material having a non-linear refractive index effect is 3
The following nonlinear susceptibility χ ⁽³⁾ is 1 × 10 ⁻¹³ esu
7. The nonlinear optical fiber according to claim 6, wherein: 8. The organic substance having a nonlinear refractive index effect,
Either a molecular crystalline material, or an ionic crystalline material, or an π-electron conjugated oligomer or polymer material, or an organic dispersion in which a combination thereof is dispersed in an organic solvent or a polymer material having excellent transparency, or The nonlinear optical fiber according to claim 6, wherein the nonlinear optical fiber is a combination thereof. 9. The method according to claim 1, wherein the organic substance and the organic solvent in which the organic substance is dispersed or the polymer material having excellent transparency are those in which hydrogen constituting the molecules is deuterated or fluorinated. The nonlinear optical fiber according to any one of claims 6 to 8. 10. The material of the core a2 is GeO ₂ —Si.
O ₂ , P ₂ O ₅ —SiO ₂ , GeO ₂ —P ₂ O ₅ —Si
O ₂ or a SiO 2 _-F, either of the nonlinear optical fiber of claim 9 wherein each of said cladding material from claim 6, characterized in that the SiO _2. 11. The material for the stress applying portion is SiO ₂ —B ₂ O.
_The nonlinear optical fiber according to any one of claims 6 to 10, wherein the nonlinear optical fiber ( ₃ ) is used. 12. An organic substance dispersion in which a hollow portion is provided in a small-diameter tube mainly composed of glass and an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency. In the nonlinear optical fiber in which the refractive index of the core portion is controlled to be larger than the refractive index of the cladding portion by adjusting the dispersion concentration or the composition of the dispersion to form the core portion b0, A non-linear optical fiber, wherein a material obtained by fluorinating hydrogen constituting the molecule is used as an organic solvent for dispersing the organic substance or a polymer material having excellent transparency. 13. The organic substance having a nonlinear refractive index effect,
1 × 10 ⁻¹³ es as the third-order nonlinear susceptibility χ ⁽³⁾
13. The nonlinear optical fiber according to claim 12, wherein the number is not less than u. 14. The organic substance having a nonlinear refractive index effect may be a molecular crystalline material, an ionic crystalline material, a π-electron conjugated oligomer or polymer material, or a combination thereof, as an organic solvent or a transparent material. 14. The nonlinear optical fiber according to claim 12, wherein the non-linear optical fiber is any one of an organic dispersion dispersed in an excellent polymer material or a combination thereof. 15. A nonlinear optical device in which an optical medium having a nonlinear refractive index effect is sandwiched between two polarizers arranged so that their polarization axes are orthogonal to each other. An organic substance having an effect is dispersed in an organic solvent or a polymer material having excellent transparency, and the refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion. A core a1 having a refractive index equal to that of the organic material dispersion, the core having glass as a main component and having a center around a hollow portion for enclosing the organic material dispersion, a1 comprising a core b1 comprising the organic substance dispersion encapsulated in the center of the core a1;
A nonlinear optical fiber having a structure having a cladding having glass as a main component and having a refractive index smaller than that of the core a1, which is disposed outside the optical fiber 1; 16. A nonlinear optical device in which an optical medium having a nonlinear refractive index effect is sandwiched between two polarizers arranged so that their polarization axes are orthogonal to each other. Non-linear optical fiber in which a dispersion of an organic substance whose refractive index is finely controlled by dispersing it in a polymer material excellent in water and adjusting the dispersion concentration or the composition of the dispersion is enclosed in a hollow small-diameter tube mainly composed of glass. A core a2 having a hollow portion for enclosing the organic substance dispersion as a center and having glass as a main component and having a refractive index equal to that of the organic substance dispersion;
B2 comprising the organic substance dispersion encapsulated in the center of
And a cladding disposed outside of the core a2 and having glass as a main component and having a lower refractive index than the core a2, and at least two stress applying portions mainly composed of glass disposed in the cladding, The stress applying portion faces the core a2 across the core a2 and is separated from the core a2. The thermal expansion coefficient of the stress applying portion is different from the thermal expansion coefficient of the clad, and a non-axisymmetric stress is applied to the core a2. A nonlinear optical device using a nonlinear optical fiber having a structure to be added. 17. In a nonlinear optical device in which an optical medium having a nonlinear refractive index effect is sandwiched between two polarizers arranged so that the polarization axes are orthogonal to each other, glass is mainly used as the optical medium having a nonlinear refractive index effect. A hollow portion is provided in a small-diameter tube as a component, and an organic material dispersion in which an organic material having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency is sealed in the hollow portion to form a core portion b0. ,
A nonlinear optical fiber in which the refractive index of the core is controlled to be larger than the refractive index of the clad by adjusting the dispersion concentration or the composition of the dispersion, and wherein the organic substance and the organic solvent in which the organic substance is dispersed are controlled. Alternatively, a non-linear optical device using a non-linear optical fiber using, as a polymer material having excellent transparency, deuterated or fluorinated hydrogen constituting the molecules. 18. It has two entrance ends and two exit ends,
A semi-transmissive mirror or optical coupler for dividing the signal light incident on one incident end into two output ends substantially equally, and an optical medium having a nonlinear refractive index effect connected to the two output ends of the semi-transparent mirror or optical coupler In a nonlinear optical device having a structure in which control light propagates in the optical medium in almost one direction only, as an optical medium having a nonlinear refractive index effect, an organic substance having a nonlinear refractive index effect is excellent in organic solvent or transparency. A non-linear optical fiber in which an organic dispersion, which is dispersed in a polymer material and whose refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion, is enclosed in a hollow small-diameter tube mainly composed of glass. A core a1 having a hollow portion for enclosing the organic dispersion and having glass as a main component and having the same refractive index as the organic dispersion. Non-linear optical fiber having a structure having a core b1 made of the organic dispersion sealed in the center of the core a1 and a clad disposed outside the core a1 and mainly composed of glass and having a smaller refractive index than the core a1. A nonlinear optical device characterized by using: 19. It has two entrance ends and two exit ends,
A semi-transmissive mirror or optical coupler for dividing the signal light incident on one incident end into two output ends substantially equally, and an optical medium having a nonlinear refractive index effect connected to the two output ends of the semi-transparent mirror or optical coupler In a nonlinear optical device having a structure in which control light propagates in the optical medium in almost one direction only, as an optical medium having a nonlinear refractive index effect, an organic substance having a nonlinear refractive index effect is excellent in organic solvent or transparency. A non-linear optical fiber in which an organic dispersion, which is dispersed in a polymer material and whose refractive index is finely controlled by adjusting the dispersion concentration or the composition of the dispersion, is enclosed in a hollow small-diameter tube mainly composed of glass. A core a2 having a hollow portion for enclosing the organic dispersion and having glass as a main component and having the same refractive index as the organic dispersion. A core b2 made of the organic dispersion sealed in the center of the core a2, a clad disposed outside the core a2 and mainly composed of glass and having a lower refractive index than the core a2, and disposed in the clad; And at least two stress applying portions mainly composed of glass, wherein the stress applying portions are opposed to each other with the core a2 interposed therebetween and are separated from the core a2. A nonlinear optical device characterized by using a nonlinear optical fiber having a structure for applying a non-axisymmetric stress to the core a2, unlike the thermal expansion coefficient of the clad. 20. It has two entrance ends and two exit ends,
A semi-transmissive mirror or optical coupler for dividing the signal light incident on one incident end into two output ends substantially equally, and an optical medium having a nonlinear refractive index effect connected to the two output ends of the semi-transparent mirror or optical coupler In a nonlinear optical device having a structure in which control light propagates in the optical medium in almost one direction only, as an optical medium having a nonlinear refractive index effect, a hollow portion is provided in a small-diameter tube mainly composed of glass, An organic substance dispersion in which an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency is sealed in the hollow portion to form a core portion b0, and the dispersion concentration or the composition of the dispersion is adjusted. Thereby, a nonlinear optical fiber in which the refractive index of the core portion is controlled to be larger than the refractive index of the cladding portion, wherein the organic substance and the organic substance are dispersed. As the polymer material which is excellent in machine solvent or transparency, non-linear optical device, characterized by using a nonlinear optical fiber used as the hydrogen constituting their molecular was fluorinated. 21. After one light beam is split into two light beams by a semi-transmissive mirror or an optical coupler, and two optical media are used to pass through different paths, a relative optical path length difference is given. In an optical device for recombining two light beams, an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency in one of the optical media, and the dispersion concentration or the composition of the dispersion is adjusted. A non-linear optical fiber in which an organic substance dispersion whose refractive index is finely controlled is sealed in a hollow small-diameter tube mainly composed of glass, the glass having a hollow portion for enclosing the organic substance dispersion as a center. A1 having a refractive index equal to that of the organic substance dispersion, and a core b1 comprising the organic substance dispersion encapsulated in the center of the core a1 and the core a1.
A nonlinear optical fiber having a structure having a cladding having glass as a main component and having a refractive index smaller than that of the core a1, which is disposed outside the optical fiber 1; 22. A light beam is split into two light beams by a semi-transmissive mirror or an optical coupler, and two optical media are used to pass through different paths to give a relative optical path length difference. In an optical device for recombining two light beams, an organic substance having a nonlinear refractive index effect is dispersed in an organic solvent or a polymer material having excellent transparency in one of the optical media, and the dispersion concentration or the composition of the dispersion is adjusted. A non-linear optical fiber in which an organic substance dispersion whose refractive index is finely controlled is sealed in a hollow small-diameter tube mainly composed of glass, the glass having a hollow portion for enclosing the organic substance dispersion as a center. A2 having a refractive index equal to that of the organic dispersion, and a core b2 comprising the organic dispersion encapsulated in the center of the core a2 and the core a2.
A cladding having a refractive index smaller than that of the core a2, which is mainly composed of glass, and which is disposed outside the cladding 2; and at least two stress applying sections mainly composed of glass, which are arranged in the cladding. Has a structure in which the core a2 is opposed to and separated from the core a2, the coefficient of thermal expansion of the stress applying portion is different from the coefficient of thermal expansion of the cladding, and a non-axisymmetric stress is applied to the core a2. A nonlinear optical device using a nonlinear optical fiber. 23. After one light beam is split into two light beams by a semi-transmissive mirror or an optical coupler, and two optical media are used to pass through different paths, a relative optical path length difference is given. In an optical device for re-combining two light beams, a hollow portion is provided in one of the optical media in a small-diameter tube mainly composed of glass, and an organic substance having a nonlinear refractive index effect is converted into an organic solvent or a polymer material having excellent transparency. The organic substance dispersion dispersed in the hollow portion is sealed into a core portion b0,
A nonlinear optical fiber in which the refractive index of the core is controlled to be larger than the refractive index of the clad by adjusting the dispersion concentration or the composition of the dispersion, and wherein the organic substance and the organic solvent in which the organic substance is dispersed are controlled. Alternatively, a non-linear optical device using a non-linear optical fiber using, as a polymer material having excellent transparency, deuterated or fluorinated hydrogen constituting the molecules.