JPH0756096A - Optical modulator, optical microswitch and electrostatic microactuator - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a compact and highly efficient optical modulator, an optical microswitch, or a compact and highly controllable electrostatic microactuator. A pair of diffractive plates 3 and 4 which are arranged substantially perpendicular to the optical axis of incident light and substantially parallel to each other and which have a phase grating of a pitch p which mainly transmits ± first-order diffracted light is provided. The optical modulator is provided with a driving means 6 for moving at least one of the diffractive plates in the direction substantially orthogonal to the grating formation direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical modulator mainly used in optical communication, an optical computer, etc. for controlling the amount of incident light, an optical microswitch for switching, and a minute displacement using electrostatic force. The present invention relates to an electrostatic microactuator for generating

[0002]

2. Description of the Related Art As an example of a conventional optical modulator or optical switch, an optical waveguide type device using LiNbO ₃ which is an electro-optic crystal will be described with reference to FIGS. Figure 17
FIG. 18 is a plan view of an optical waveguide type element called a directional coupling type, and FIG. 18 is a sectional view thereof. In the figure, 1a and 1b are optical waveguides, 2a and 2b are electrodes, 3 is LiNbO ₃ , and 4 is SiO.
_Two buffer layers are shown respectively. The optical waveguides 1a and 1b using this LiNbO ₃ are made by a method of thermally diffusing Ti metal patterned on the substrate 3 into desired waveguide dimensions. The control electrodes 2a and 2b for applying an electric field to the substrate 3 are generally made of Si in order to prevent light absorption by the electrode material.
Optical waveguides 1a, 1b through the O ₂ optical buffer layer 4
Formed on.

When the two optical waveguides 1a and 1b are located very close to each other, a light wave energy is transferred between the two optical waveguides. The amount of transfer of light wave energy depends on the difference between the propagation constant and the overlap (coupling strength) of the leakage electromagnetic fields of the two guided modes. In the optical waveguide using the electro-optic crystal,
The coupling strength and phase difference between the guided modes can be controlled by an external voltage, and light intensity modulation or switching can be performed.

FIG. 19 shows this state. C
Is the coupling coefficient, and Δβ = β1-β2 is the phase constant of the waveguide mode of the waveguide 1 and the waveguide 2. Phase matching conditions;
Δβ = 0 is satisfied. For example, when viewed at the position of Z = L ₀ , it can be seen that 100% optical switching can be obtained by changing Δβ / C depending on the voltage.

[0005]

However, such an optical waveguide type optical modulator or optical switch has drawbacks such as a complicated manufacturing process and a large coupling loss of input and output of light to and from the optical waveguide. Had.

According to the present invention, a pair of diffractive plates that mainly transmit ± 1st order diffracted light are provided, and at least one diffractive plate of the pair of diffractive plates is movable in a direction substantially orthogonal to the grating formation direction. An object of the present invention is to provide a small-sized optical modulator or optical switch that has a simple manufacturing process, has a small coupling loss of light input and output to an optical waveguide, and has a small size.

[0007]

An optical modulator according to claim 1 of the present application for solving the above-mentioned problems is mainly arranged substantially perpendicular to an optical axis of incident light and substantially parallel to each other. A pair of diffractive plates having a phase grating with a pitch p that transmits ± first-order diffracted light is provided, and a driving means is provided for moving at least one diffractive plate of the pair of diffractive plates in a direction substantially orthogonal to the grating formation direction. It is an optical modulator characterized by that.

Further, the optical microswitch according to claim 2 of the present application is arranged substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and the phase grating having the pitch p mainly transmitting the ± 1st order diffracted light. A pair of diffractive plates having
The optical microswitch is provided with a driving unit that makes it possible to move to a position where the relative displacement of the pair of diffractive plates in a direction substantially orthogonal to the grating formation direction is an integral multiple of p / 2.

In the electrostatic microactuator according to claim 3 of the present application, the first and second light-transmissive substrates, on which phase gratings with a pitch p for transmitting mainly ± first-order diffracted light are formed, are provided with an optical axis of incident light. Movable comb tooth-shaped portions that are arranged substantially perpendicular to each other and substantially parallel to each other, and that are composed of a plurality of protrusions in the peripheral portion of at least one of the first or second light-transmissive substrates. And a fixed comb tooth shaped portion for relatively displacing the first and second light transmissive substrates by electrostatic force is formed so as to face each comb tooth of the movable comb tooth shaped portion. An electrostatic microactuator having a third substrate.

On the other hand, in the electrostatic microactuator according to claim 4 of the present application, first and second comb-shaped portions formed by a phase grating having a pitch p that mainly transmits ± first-order diffracted light and a plurality of protrusions are formed. The second light-transmissive substrate is arranged so as to be substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and the comb-tooth-shaped portions face each other. The electrostatic microactuator is characterized in that an electrode for relatively displacing the transparent substrate by an electrostatic force is provided on the comb-shaped portion.

[0011]

The optical modulator according to claim 1 of the present application is a pair which is arranged substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and which has a phase grating with a pitch p which mainly transmits ± first-order diffracted light. A diffractive plate is provided, and at least one diffractive plate of the pair of diffractive plates is provided with a driving means that is movable in a direction substantially orthogonal to the grating formation direction. It is an optical modulator that controls the interference state of light transmitted through two diffractive plates and modulates the intensity of transmitted light.

Further, the optical microswitch according to claim 2 of the present application is arranged substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and the phase grating having the pitch p which mainly transmits the ± first-order diffracted lights. A pair of diffractive plates having
The light transmitted through the two diffractive plates is provided by providing a driving means capable of moving the relative displacement of the pair of diffractive plates in a direction substantially orthogonal to the grating formation direction to a position that is an integral multiple of p / 2. It is an optical microswitch that controls the interference state of (1) and captures the binary value of transmitted light as 0 or 1.

In the electrostatic microactuator according to claim 3 of the present application, the first and second light-transmissive substrates, on which phase gratings having a pitch p for transmitting mainly ± first-order diffracted light are formed, are provided with an optical axis of incident light. Movable comb tooth-shaped portions that are arranged substantially perpendicular to each other and substantially parallel to each other, and that are composed of a plurality of protrusions in the peripheral portion of at least one of the first or second light-transmissive substrates. And a fixed comb tooth shaped portion for relatively displacing the first and second light transmissive substrates by electrostatic force is formed so as to face each comb tooth of the movable comb tooth shaped portion. By providing the third substrate, the phase gratings formed on the first and second light transmissive substrates are relatively displaced to thereby modulate the intensity of incident light.

Further, in the electrostatic microactuator according to claim 4 of the present application, the first and first comb-tooth-shaped portions formed by a phase grating having a pitch p that mainly transmits ± first-order diffracted light and a plurality of protrusions are formed. The second light-transmissive substrate is arranged so as to be substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and the comb-tooth-shaped portions face each other. By disposing the electrode for relatively displacing the transparent substrate by the electrostatic force in the comb tooth-shaped portion, the phase gratings formed on the first and second light transmissive substrates are relatively displaced, It is an electrostatic microactuator that modulates the intensity of incident light.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical modulator according to claim 1 of the present application will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a side sectional view of an embodiment of an optical modulator according to claim 1 of the present application. Figure 2
FIG. 2 is a view on arrow A in FIG. 1.

In FIG. 1 and FIG. 2, 1 is a light source composed of a semiconductor laser or a light emitting diode having a relatively high coherence, 2 is a collimator lens for collimating the light emitted from the light source 1, and 3 is a rectangular wave section. Has a phase grating of
The first diffractive plate 4 arranged perpendicularly to the optical axis has a phase grating with a rectangular wave-shaped cross section, and the direction of forming the phase grating is substantially parallel to the direction of forming the phase grating of the first diffractive plate. The second diffractive plate 5 arranged so as to be perpendicular to the optical axis is a leaf spring which is an elastic support member for movably supporting the first diffractive plate 3 in a direction orthogonal to the grating forming direction, Reference numeral 6 denotes a driving means for generating a force for moving the first diffractive plate 5. In the present embodiment, specifically, it is fixed to the magnetic film 7 formed on the surface of the elastic supporting member 5 by means such as sputtering. It is composed of an electromagnet 8. Reference numeral 10 is a condenser lens. One end of the elastic support member 5 is fixed to the second diffractive plate 4, and the other end is fixed to the fixing member 9.

The phase gratings on the first diffractive plate 3 and the second diffractive plate 4 have substantially the same pitch p and depth d. The depth d has a relationship represented by the formula (1) with respect to the wavelength λ of the light source.

| N−n ₀ | × d = (λ / 2) × (1 + 2m) Equation (1) Here, n is a material forming the first diffraction plate 3 and the second diffraction plate 4. , And n ₀ is the refractive index of the medium between the first diffraction plate 3 and the second diffraction plate 4. Further, m represents an integer of 0, ± 1, ± 2, ...

The operation of the optical modulator configured as described above will be described. The light emitted from the light source 1 is collimated by the collimator lens 2 and then enters the first diffraction plate 3. Now, the depth d of the phase gratings of the first diffraction plate 3 and the second diffraction plate 4 is set to the depth shown in the equation (1). Therefore, it is known from Fourier optic theory that the components of diffracted light of even orders including the 0th order become 0, and most of the light energy (about 40% each) is concentrated in the ± 1st order diffracted lights. The ± first-order diffracted light diffracted by the first diffractive plate 3 is diffracted again by the second diffractive plate 4. Even at this time, most of the light energy in the ± 1st order diffracted light
Concentrates.

Now, the diffracted light emitted from the second diffractive plate 4 will be represented by (s, t). Where s is the first
Of the diffractive plate 3 and t are the diffractive orders of the second diffractive plate 4, respectively.

Here, the fixed electromagnet 8 is energized and the magnetic attraction / repulsion generated between the fixed electromagnet 8 and the magnetic film 7 is used to
The first diffractive plate 3 is moved in the direction indicated by the arrow in FIGS. Generally, when the diffraction grating is translated by Δ, a phase change corresponding to the diffraction order m is generated.

FIG. 3 shows the relationship between the displacement of the diffraction grating and the phase change. For the convenience of illustration, the case of the reflection type diffraction grating is shown, but the phenomenon described below can be similarly explained in the case of the transmission type diffraction grating. In addition, FIG.
FIG.

From FIGS. 3 and 4, the optical path length difference δ before and after the movement of the diffraction grating is given by equation (2).

Δ = (a′b′c′−abc) = eb′−bd = Δ (sin θs + sin θm) Equation (2) Therefore, the phase difference φ is given by Equation (3).

Φ = 2πΔ (sin θs + sin θm) / λ (3) Equation On the other hand, the diffraction formula is given by Equation (4).

P (sin θs + θm) = mλ Equation (4) Equation (3) and Equation (4) yield φ = 2πmΔ / p Equation (5), which is high for 0th-order diffracted light. It can be seen that a phase change proportional to the diffraction order m occurs in the next diffracted light, and the sign of φ changes depending on whether the order m is positive or negative.

As described above, the diffracted light phase-modulated by the displacement of the phase grating on the first diffraction plate 3 can be interfered by the phase grating on the second diffraction plate 4 which is a fixed diffraction grating. The optical path is changed to.

FIG. 5 shows a model of the interference caused by the two phase gratings. In FIG. 5, 20 is a diffraction grating and 21
Reference numerals 22 and 22 denote mirrors. The + m-th order diffracted light and the −m-th order diffracted light diffracted by the diffraction grating 20 are subjected to optical path conversion by a mirror 21 and a mirror -22. The lights that are parallel to each other cause interference.

The correspondence between this embodiment and this model is that the diffraction grating 20 and the first diffraction plate 3 in FIG.
1 and the mirror 22 correspond to the second diffraction plate 4. That is, the second diffractive plate, which is a fixed diffractive plate, is considered to be equivalent to a mirror group including a plurality of mirrors arranged at different angles corresponding to the diffraction order.
Therefore, only the first diffractive plate 3, which is a movable diffractive plate, is related to the phase of the diffracted light.

Therefore, it has a phase of φ = 2πΔ / p
Diffracted light of (m, -m) and a phase of φ = -2πΔ / p (-m,
The light intensity of the interference wave obtained by the interference with the diffracted light of (m) is m / m, where p is the pitch of the phase grating on the first diffraction plate 3.
produces a sine wave with a frequency of p.

FIG. 6 illustrates the change in the intensity of the interference light with the horizontal axis representing the displacement of the first diffraction plate 3. As shown in FIG. 6, the intensity of the interference light has a maximum value of 1 when the displacement is an even multiple of p / 2, and the intensity of the interference light is a minimum value of 0 when the displacement is an odd multiple of p / 2.
Take

Therefore, a drive current is supplied to the fixed electromagnet 8 from a power source (not shown), and the magnetic attraction or repulsive force acting between the fixed electromagnet 8 and the magnetic film 7 is balanced by the elastic force of the elastic support member 5. By displacing the first diffraction plate 3 in the direction orthogonal to the formation direction of the phase grating formed thereon, it is possible to provide an optical modulator capable of continuously modulating the interference intensity of output light from 0 to 1. .

The optical transmission efficiency of this optical modulator is about 64%, which is more than double the efficiency of the conventional optical waveguide type. Further, the pitch p of the phase grating is, for example, 5 μ
If it is created by m, optical modulation can be performed by moving it by only 2.5 μm, so that it is possible to reduce power consumption and size.

Therefore, they can be arranged in a one-dimensional array form, a two-dimensional matrix form, or arranged in multiple stages, and can be used, for example, in an optical switching device, an optical logic operation element, an optical interconnection, etc. in optical communication or an optical computer.

(Embodiment 2) Next, an optical microswitch according to claim 2 of the present application will be described with reference to the drawings. FIG. 7 is a side sectional view of an embodiment of the optical microswitch according to claim 2 of the present application. FIG. 8 is a view on arrow A in FIG. 7.

In FIGS. 7 and 8, 1 is a light source made of a semiconductor laser or a light emitting diode having a relatively high coherence, 2 is a collimator lens for collimating the light emitted from the light source 1, and 3 is a rectangular wave section. Diffractive plate having a phase grating of 4 and arranged perpendicularly to the optical axis, 4 has a phase grating with a rectangular wave-shaped cross section, and the direction of forming the phase grating is the direction of forming the phase grating of the first diffractive plate. A second diffractive plate which is arranged so as to be substantially parallel to and perpendicular to the optical axis,
Indicate condensing lenses, which have the same functions as those of the same numbers shown in FIG.

Reference numeral 15 is a position where the relative displacement of the first diffraction plate 3 and the second diffraction plate 4, which are a pair of diffraction plates, in the direction substantially orthogonal to the grating formation direction is an integral multiple of p / 2. The drive means which can be moved is shown. Details of the configuration of the driving means 15 will be described below. Reference numeral 11 denotes a movable tooth-shaped iron core having a pitch of 2p, which is twice the pitch of the phase grating, and is fixed to the end surface of the first diffraction plate 3 by means such as adhesion. 12a and 12b are fixed electromagnets, 13a and 13b
Is a permanent magnet, and the south pole 13a has a tooth-shaped iron core 11a.
And 13b is arranged so that its N pole faces the tooth-shaped iron core 11. Reference numeral 14 is a yoke that connects the N pole of the permanent magnet 13a and the S pole of the permanent magnet 13b.

Claim 2 of the present application thus constituted
The operation of the embodiment of the described optical microswitch will be described with reference to the drawings. FIG. 9 is an operation explanatory view of the driving means 15, and illustrates relative displacement between the tooth-shaped iron core 11 which is a movable portion and the electromagnets 12a and 12b which are fixed portions.

The drive unit (not shown) is configured so that a current flows through the electromagnets 12a and 12b. When a current is supplied only to the electromagnet 12b in the direction shown in FIG. 9A, the magnetic pole 3 of the electromagnet 12b acts synergistically with the magnetic force of the permanent magnet 13b, and the magnetic pole 4 of the permanent magnet 13b.
9 and the relative displacement between the movable part and the fixed part are offset by the magnetic force of
Given in (A). At this time, the magnetic poles 1 and 2 of the electromagnet 12a are magnetically balanced.

Next, in this state, when a current is applied only to the electromagnet 12a in the direction shown in FIG. 9B, the magnetic force of the magnetic pole 1 is offset by the magnetic force of the permanent magnet 13a, and the magnetic pole 2 works synergistically to move the movable portion. And the relative displacement of the fixed part is shown in Figure 9 (B)
Given in.

From the comparison between FIGS. 9A and 9B, it can be seen that the relative displacement between the fixed portion and the movable portion of the driving means 15 changes by p / 2.

Further, when currents are alternately supplied to the electromagnets 12b and 12a in the directions shown in FIGS. 9 (C) and 9 (D), they are given in FIGS. 9 (C) and 9 (D). Thus, a displacement of p / 2 is obtained. That is, by alternately exciting the electromagnets 12a and 12b which are the fixed parts, a displacement of ¼ of the pitch of the tooth-shaped iron core 11 which is the movable part, that is, ½ of the pitch of the phase grating can be obtained. Recognize. Here, the tooth-shaped iron core 11 is fixed to the first diffraction plate 3.

On the other hand, the interference light intensity, the first diffraction plate 3 and the second diffraction plate 3
6 showing the relationship with the relative displacement with respect to the diffraction plate 4, the intensity of the interference light is 1 at the position where the relative displacement is an even multiple of p / 2, and the interference is at the position where the relative displacement is an odd multiple of p / 2. It can be seen that the light intensity becomes zero.

In this embodiment, since the tooth-shaped iron core 11 is fixed to the first diffractive plate 3, the first diffractive plate 3 and the first diffractive plate 3 are alternately applied to the electromagnets 12a and 12b. 2 the relative displacement of the phase grating on the diffractive plate 4 is p / 2
Therefore, it is possible to realize an optical microswitch in which the intensity of the interference light that is output is 0 or 1.

The optical transmission efficiency of this optical switch is about 64%, which is more than double the efficiency of the conventional optical waveguide type. Furthermore, the pitch p of the phase grating is, for example, 5
If it is created in μm, it is possible to reduce power consumption and downsize because optical switching can be performed by moving it by only 2.5 μm. Therefore, they can be used in a one-dimensional array form, a two-dimensional matrix form, or arranged in multiple stages and used, for example, in an optical switching device, an optical logical operation element, an optical interconnection, etc. in optical communication or an optical computer.

(Embodiment 3) Hereinafter, an electrostatic microactuator according to claim 3 of the present application will be described with reference to the drawings. FIG. 11 is a side view of a first embodiment of the electrostatic microactuator according to claim 3 of the present application. FIG. 11 is a view on arrow A in FIG.

In FIGS. 10 and 11, 1 is a light source formed of a semiconductor laser or a light emitting diode having a relatively high coherence, 2 is a collimator lens for collimating the light emitted from the light source 1, and 10 is a condenser lens. Is. These have the same functions as those of the same numbers in FIG. 16
Is a substrate made of, for example, polysilicon or glass, in the center of which a phase grating having a depth represented by the formula (1) is formed, and in the periphery thereof, a movable comb tooth-shaped portion 17 is formed. It is formed by a technique such as etching. Polysilicon is 1.3μ used in optical communication.
It has a sufficient spectral transmittance characteristic for wavelengths in the m to 1.6 μm band. Further, an electrode is formed on each comb tooth of the movable comb tooth-shaped portion by a method such as vapor deposition.

Reference numeral 18 is a second light-transmissive substrate on which a phase grating represented by the formula (1) is formed, and reference numeral 19 is arranged so that the movable comb tooth-shaped portion 17 and each comb tooth face each other. It is a third substrate having a fixed comb-shaped portion 18. The second light transmissive substrate 18 or the third substrate 19 is formed by using a manufacturing process such as etching polysilicon or glass. Further, an electrode is formed on each comb tooth of the fixed comb tooth-shaped portion by a method such as vapor deposition. The movable comb-teeth shaped portion 17 of the first light transmissive substrate 16 and the third substrate 1
The fixed comb tooth-shaped portions 18 of 9 are arranged so as to face each other as shown in FIG.

The operation of the electrostatic microactuator of this embodiment thus constructed will be described with reference to FIGS. 10 and 11. The first light-transmissive substrate 16 is illustrated in FIG. 11 by causing an electric field to act between the electrodes of the movable comb-tooth-shaped portion 17 and the fixed comb-tooth-shaped portion 18 by a driving unit (not shown) to generate an electrostatic force. Move in the direction.
At this time, the phase grating formed on the first light transmissive substrate 16 and the second light transmissive substrate 20 is an optical modulator according to claim 1 or an optical microswitch according to claim 2. It is constructed in the same way as the example.

As a result, in the embodiment of the optical modulator according to claim 1 of the present application, the change in the intensity of the interference light is plotted as the first axis in the first embodiment.
The same characteristic as that shown in FIG. 6 by taking the displacement of the diffractive plate 3 is established between the displacement of the first light transmissive substrate and the interference light intensity in the present embodiment. That is, as shown in FIG. 6, the intensity of the interference light has a maximum value of 1 at a displacement of an even multiple of p / 2, and the intensity of the interference light has a minimum value of 0 at a displacement of an odd multiple of p / 2. At the intermediate displacement, a value of 0 to 1 will be taken in a sine wave.

Therefore, since the phase grating and the movable comb-tooth-shaped portion are integrally formed on a substrate having a light-transmitting property such as polysilicon or glass, the first substrate 1 is electrostatically actuated.
By displacing 6 in the direction orthogonal to the formation direction of the phase grating formed thereon, an electrostatic microactuator capable of continuously modulating the interference intensity of output light from 0 to 1 can be provided.

The optical transmission efficiency of this actuator is
Excluding absorption by the substrate, it is about 64%, which is more than twice the efficiency of the input / output coupling efficiency of the conventional optical waveguide type optical modulator or optical switch. Further, if the pitch p of the phase grating is made to be, for example, 5 μm, optical switching can be performed by moving it by only 2.5 μm. Therefore, the gap between the movable comb tooth-shaped portion 17 and the fixed comb tooth-shaped portion is 3
About μm is sufficient, and the efficiency of electrostatic drive can be improved.

Further, since a complicated displacement magnifying mechanism is unnecessary, the size can be reduced. Alternatively, since it is not necessary to limit the operating condition to the resonance state and to secure the displacement of the order of several 100 μm, it is possible to drive at an arbitrary frequency. In addition, since the electrostatic force generated in the comb-shaped portion acts near the center of gravity of the first substrate 22 that is the movable portion, generation of undesired resonance can be prevented, good frequency characteristics can be obtained, and high-speed operation becomes possible. Such an effect can be obtained.

Therefore, they can be arranged in a one-dimensional array form, a two-dimensional matrix form, or arranged in multiple stages, and can be used, for example, in an optical switching device, an optical logic operation element, an optical interconnection, etc. in optical communication or an optical computer.

(Embodiment 4) Another embodiment of the present invention will be described with reference to FIGS. 12 and 13. In the figure, those having the same numbers as those in FIG. 10 or FIG. 11 indicate those having the same function. Reference numeral 22 is a first light-transmissive substrate that is a movable portion, and a phase grating 21 is formed in a part of the first light-transmissive substrate. The phase grating on the second light transmissive substrate 20 is arranged to face the phase grating 21.

With the electrostatic microactuator having such a structure, the electrostatic force generated in the comb-tooth-shaped portion acts near the center of gravity of the first substrate 22 which is the movable portion.
The occurrence of undesired resonance can be prevented, good frequency characteristics can be obtained, and high-speed operation becomes possible. Furthermore, an output signal as shown in FIG. 6 is obtained with respect to the displacement of the electrostatic microactuator by the phase grating 21 formed on a part of the movable portion and the phase grating on the second light transmissive substrate 20. The displacement of the actuator can be directly detected from this output signal, and the velocity signal or acceleration signal can be easily obtained by appropriate signal processing such as differentiation. Therefore, according to this embodiment, it is possible to provide the electrostatic microactuator with the position, velocity and acceleration sensors.

(Embodiment 5) Hereinafter, an electrostatic microactuator according to claim 4 of the present application will be described with reference to the drawings. FIG. 14 is a side view of an embodiment of the electrostatic microactuator according to claim 4 of the present application.
FIG. 15 shows the shape and configuration of the first light transmissive substrate 16 viewed from the direction of arrow A shown in FIG. FIG. 16 is a perspective view of an essential part of the second light transmissive substrate 23.

In FIGS. 14, 15 and 16, 1
Is a light source composed of a semiconductor laser or a light emitting diode having a relatively high coherence, 2 is a collimator lens for collimating the light emitted from the light source 1, and 10 is a condenser lens. These have the same functions as those with the same numbers in FIG. Reference numeral 16 denotes a substrate made of, for example, polysilicon or glass, in the center of which a phase grating having a depth represented by the formula (1) is provided, and at the periphery thereof, a movable comb-tooth shaped portion 17 is provided. , Each is formed by a method such as etching. Note that polysilicon has a sufficient spectral transmittance characteristic for wavelengths in the 1.3 μm to 1.6 μm band used in optical communication. Further, an electrode is formed on each comb tooth of the movable comb tooth-shaped portion by a method such as vapor deposition.

Reference numeral 23 is a second light-transmitting substrate, on which a phase grating represented by the formula (1) is formed, and a comb-tooth shaped portion 24 is formed on the periphery thereof by a method such as etching. . Further, as shown in FIG. 16, the comb tooth-shaped portion 24 is formed so as to be vertically long in the depth direction of the phase grating, and an electrode is formed on each comb tooth by a method such as vapor deposition. The comb-shaped portion 1 of the first light-transmissive substrate 16
7 and the comb-tooth-shaped portion 24 of the second light-transmissive substrate 23 shown in FIG.
4, they are arranged so as to face each other.

The operation of this embodiment thus constructed will be described with reference to FIGS. 14 to 16. The comb-tooth-shaped portion 17 and the comb-tooth-shaped portion 2 are driven by a driving unit (not shown).
By applying an electric field between the electrodes of No. 4 to generate an electrostatic force, the first light transmissive substrate 16 and the second light transmissive substrate 23
And are relatively displaced in the directions shown in FIG.
At this time, the phase grating formed on the first light transmissive substrate 16 and the second light transmissive substrate 23 is the optical modulator according to claim 1 or the optical microswitch according to claim 2 of the present application. The configuration is the same as that of the embodiment.

As a result, regarding the relationship between the relative displacement between the first light transmissive substrate 16 and the second light transmissive substrate 23 and the interference light intensity in this embodiment, the same characteristics as in FIG. 6 can be obtained. Becomes

That is, as shown in FIG. 6, the intensity of the interference light has a maximum value of 1 when the displacement is an even multiple of p / 2, and the minimum value of the intensity of the interference light is 0 when the displacement is an odd multiple of p / 2. However, the intermediate displacement takes a value of 0 to 1 sinusoidally. Therefore, by integrally forming the phase grating and the movable comb-teeth-shaped portion on a substrate having a light-transmitting property, such as polysilicon or glass, the first light-transmitting substrate 16 and the second light-transmitting substrate 16 are caused by electrostatic force. An electrostatic microactuator capable of continuously modulating the interference intensity of output light from 0 to 1 by relatively displacing the substrate 23 in a direction orthogonal to the formation direction of the phase grating formed thereon. it can.

The optical transmission efficiency of this actuator is about 64% excluding the absorption by the substrate, which is more than twice as high as the input / output coupling efficiency of the conventional optical waveguide type optical modulator or optical switch. To be Further, if the pitch p of the phase grating is made to be, for example, 5 μm, optical switching can be performed by moving it by only 2.5 μm. Therefore, the gap between the comb-shaped portions 17 and 24 is 3 μm.
The degree is sufficient and the efficiency of electrostatic drive can be improved.

Further, since a complicated displacement magnifying mechanism is unnecessary, the size can be reduced. Alternatively, since it is not necessary to limit the operating condition to the resonance state and to secure the displacement of the order of several 100 μm, it is possible to drive at an arbitrary frequency. In addition, since the electrostatic force generated in the comb-shaped portion acts near the center of gravity of the first substrate 22 that is the movable portion, it is possible to prevent undesired resonance from occurring,
It is possible to obtain the operational effect that good frequency characteristics are obtained and high-speed operation is possible.

Therefore, they can be arranged in a one-dimensional array form, a two-dimensional matrix form, or arranged in multiple stages, and can be used, for example, in an optical switching device, an optical logic operation element, an optical interconnection, etc. in optical communication or an optical computer. In addition, as compared with the electrostatic microactuator according to claim 3 of the present application, there is an effect that the number of substrates can be reduced by one.

As another embodiment of the invention according to claim 4 of the present application, a configuration similar to that shown in FIGS. 12 and 13 as a second embodiment of the electrostatic microactuator according to claim 3 of the present application. Can be considered. That is, by forming the phase gratings in the regions where the first light transmissive substrate 16 and the second light transmissive substrate 23 face each other, the electrostatic force generated in the comb tooth-shaped portion acts near the center of gravity of the movable portion. Therefore, generation of undesired resonance can be prevented, good frequency characteristics can be obtained, and high speed operation can be achieved.

Furthermore, an output signal as shown in FIG. 6 is obtained for the displacement of the electrostatic microactuator by the phase grating formed in a part of the movable portion. The displacement of the actuator can be directly detected from this output signal, and the velocity signal or acceleration signal can be easily obtained by appropriate signal processing such as differentiation. Therefore, according to this embodiment, it is possible to provide the electrostatic microactuator with the position, velocity and acceleration sensors.

[0069]

As described above, the optical modulator according to claim 1 of the present application is arranged substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and mainly transmits the ± 1st order diffracted light. Providing a pair of diffraction plates having a phase grating with a pitch p,
By changing the relative displacement between the two diffractive plates provided with a driving means for moving at least one diffractive plate of the pair of diffractive plates in a direction substantially orthogonal to the grating formation direction,
It is possible to provide a compact and efficient optical modulator that controls the interference state of light transmitted through a single diffractive plate and modulates the intensity of transmitted light.

Further, the optical microswitch according to claim 2 of the present application is arranged substantially perpendicular to the optical axis of the incident light and substantially parallel to each other, and the phase grating having the pitch p mainly transmitting the ± 1st order diffracted light. A pair of diffractive plates having
The light transmitted through the two diffractive plates is provided by providing a driving means capable of moving the relative displacement of the pair of diffractive plates in a direction substantially orthogonal to the grating formation direction to a position that is an integral multiple of p / 2. A small and highly efficient optical microswitch capable of controlling the interference state of (1) and controlling the intensity of transmitted light to be a binary value of 0 or 1.

In the electrostatic microactuator according to claim 3 of the present application, the first and second light-transmissive substrates on which phase gratings with a pitch p for transmitting mainly ± first-order diffracted light are formed are provided with an optical axis of incident light. Movable comb tooth-shaped portions that are arranged substantially perpendicular to each other and substantially parallel to each other, and that are composed of a plurality of protrusions in the peripheral portion of at least one of the first or second light-transmissive substrates. And a fixed comb tooth shaped portion for relatively displacing the first and second light transmissive substrates by electrostatic force is formed so as to face each comb tooth of the movable comb tooth shaped portion. By providing the third substrate, the phase gratings formed on the first and second light-transmissive substrates are relatively displaced to modulate the intensity of the incident light, which is a small static controllable device. Electric microactuator provided That.

Further, in the electrostatic microactuator according to claim 4 of the present application, the first and the second comb-shaped portions formed by a phase grating having a pitch p that mainly transmits ± first-order diffracted light and a plurality of protrusions are formed. The second light-transmissive substrate,
Almost perpendicular to the optical axis of the incident light and parallel to each other,
Also, the comb tooth-shaped portions are arranged so as to face each other,
A phase grating formed on the first and second light transmissive substrates by providing electrodes on the comb-tooth-shaped portion that relatively displace the first and second light transmissive substrates by electrostatic force. It is possible to provide a small electrostatic microactuator that modulates the intensity of incident light by relatively displacing the electrostatic microactuator.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of an embodiment of an optical modulator of the present invention.

FIG. 2 is a view of the optical modulator of the embodiment as seen from the direction of arrow A in FIG.

FIG. 3 is an explanatory view of the principle of the optical modulator of the same embodiment.

FIG. 4 is an explanatory view of the principle of the optical modulator of the same embodiment.

FIG. 5 is an explanatory view of the principle of the optical modulator of the same embodiment.

FIG. 6 is a characteristic diagram of the optical modulator of the same embodiment.

FIG. 7 is a side view showing the configuration of an embodiment of the optical microswitch of the present invention.

FIG. 8 is a view of the optical microswitch of the embodiment as seen from the direction of arrow A in FIG. 7.

FIG. 9 is an operation explanatory diagram of the optical microswitch of the embodiment.

FIG. 10 is a side view of the first embodiment of the electrostatic microactuator according to claim 3 of the present application.

FIG. 11 is a view of the electrostatic microactuator of the same embodiment as seen in the direction of arrow A in FIG.

FIG. 12 is a plan view of a main part in another embodiment of the electrostatic microactuator according to claim 3 of the present application.

FIG. 13 is a side view of the electrostatic microactuator of the embodiment.

FIG. 14 is a side view of an embodiment of the electrostatic microactuator according to claim 4 of the present application.

FIG. 15 is a view of the electrostatic microactuator of the same embodiment taken along arrow A in FIG.

FIG. 16 is a perspective view of a main part of the electrostatic microactuator of the example.

FIG. 17 is a plan view showing the configuration of a conventional optical switch.

FIG. 18 is a sectional view showing the configuration of a conventional optical switch.

FIG. 19 is a characteristic diagram of a conventional optical switch.

[Explanation of symbols]

 1 Light Source 3 First Diffraction Plate 4 Second Diffraction Plate 16 First Light Transmissive Substrate 19 Third Substrate 20 Second Light Transmissive Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Fukui 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A pair of phase plates, which are arranged substantially perpendicular to the optical axis of the incident light and are substantially parallel to each other, and which have a phase grating with a pitch p for transmitting mainly ± first-order diffracted light, are provided. An optical modulator comprising: a driving unit that allows at least one of the diffraction plates to move in a direction substantially orthogonal to the grating formation direction. 2. A pair of phase plates, which are arranged substantially perpendicular to the optical axis of the incident light and are substantially parallel to each other, and which have a phase grating with a pitch p for transmitting mainly ± 1st order diffracted light, are provided. An optical microswitch comprising a driving unit that is movable to a position where a relative displacement of the diffractive plate in a direction substantially orthogonal to the grating formation direction is an integral multiple of p / 2. 3. A first and a second light-transmissive substrate, on which a phase grating having a pitch p for transmitting mainly ± 1st order diffracted light is formed, are substantially perpendicular to an optical axis of incident light and are substantially parallel to each other. The movable comb-tooth-shaped portion formed of a plurality of protrusions is provided on the periphery of at least one of the first or second light-transmissive substrates, and the first and second light-transmissive substrates are disposed. And a third substrate formed so that the fixed comb-teeth-shaped portion for relatively displacing the light-transmissive substrate by electrostatic force faces each comb-teeth of the movable comb-teeth-shaped portion. Electrostatic micro actuator. 4. A first and a second light-transmissive substrate formed with a comb-tooth-shaped portion formed of a phase grating having a pitch p which mainly transmits ± 1st-order diffracted light and a plurality of protrusions. The first comb-shaped portions are arranged substantially perpendicular to the axis and substantially parallel to each other, and the comb-shaped portions face each other.
An electrostatic microactuator characterized in that an electrode for relatively displacing the second light transmissive substrate by an electrostatic force is provided in the comb-shaped portion.