JP2001091912A - Optical element and demultiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element which is capable of switching photonic band structure dynamically or is capable of performing the switching operation and a demultiplexer using an optical waveguide in a photonic crystal. SOLUTION: This optical element uses plural optical media whose refractive indexes are changed by an external field and certain two refractive indexes among plural optical media are made to become equal or are made to become roughly equal under the certain condition of the external field. The optical element can perform the switching operation between two largely different photonic structure dynamically only by changing the condition of the external field by setting a distribution pattern which is to be sensed by the light to desired crystal structure, the desired shape of a lattice point and a desired cycle under these two conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical device and a duplexer. More specifically, the present invention relates to an active optical element and a duplexer that enable a photonic band structure to be changed by changing an external field such as light or an electric field in a photonic crystal to enable an optical switching operation.

[0002]

2. Description of the Related Art A "photonic crystal" in which two types of optical media having different refractive indexes are periodically arranged in the order of the wavelength of light.
In a structure called, the relationship between the wave number and frequency of light, that is, the photon energy, forms a band structure due to periodic changes in the refractive index, so that the energy of electrons in a semiconductor shows a band structure in a periodic potential. Show.

[0003] In a photonic crystal, a wavelength region called a "photonic band gap" in which light does not propagate in any direction can appear (E. Yablon).
ovitch, Phys. Rev. Lett. 58 (20), 2059 (1987)), exhibiting very large optical anisotropy and dispersibility. Therefore, utilizing these characteristics, control of spontaneous emission light, an optical waveguide having a very small radius of curvature of a bend, a polarizing element, a duplexer, and the like have been proposed, and expectations for application in various fields are increasing.

However, conventionally, except for the three examples described below, photonic crystals have been used as "passive elements", and there have been few proposals to use them as "active elements". That is, most of the conventionally proposed photonic crystals determine the optical characteristics of the photonic crystal by a refractive index distribution fixed in space. For example, in a duplexer, light is split in a specific direction. The wavelength (frequency) of the incoming light is fixed, and the frequency of the light extracted in a specific direction cannot be switched. Further, it has not been possible to dynamically switch to which of the branches provided in the waveguide the light is guided.

[0005] The following three proposals use a photonic crystal as an "active element" having a switching function.

(1) One is that a photonic crystal is provided with an ultrasonic generator or a temperature controller for disturbing the periodicity and destroying the band structure. In this way, a delay effect of a photonic crystal used as a light delay device is to be developed or eliminated (Toto, et al., JP-A-10-83005).

(2) Another one is a one-dimensional photonic crystal in which an electro-optic material is sandwiched between diffraction gratings which are arranged to face each other and have a metal film formed on the surface. By applying a voltage between the opposing metal films, the refractive index of the electro-optical material changes, and the position of the band gap in the one-dimensional direction changes, thereby turning on light transmission at a wavelength near the band edge.
/ OFF (Totori,
And JP-A-10-83005).

(3) A third proposal is to irradiate a photonic crystal containing a semiconductor as a constituent element thereof with circularly polarized light as control light, thereby changing the distribution of spins in the photonic crystal material, that is, complex refraction. By changing the ratio, the photonic band structure is changed to switch the light transmitted through the photonic crystal (Takeuchi, Nishikawa, JP-A-10-90634).

[0009]

However, these three proposals still have problems to be solved in the points described below.

[0010] That is, the proposal of the above (1) merely switches between expressing and eliminating the function as a photonic crystal, and actively changing the manner of expressing the function as a photonic crystal. Not something. Therefore, it cannot be used for the direction control of the duplexer, the branch control of the optical waveguide, and the like.

Further, the proposal of the above (2) can be applied only to a one-dimensional photonic crystal structurally, and
Regarding large dispersion properties in three dimensions or three dimensions, and properties as an excellent waveguide, it cannot be used.

The proposal of the above (3) is to change the band structure by changing the complex refractive index of the optical medium constituting the photonic crystal, and to change the periodicity and symmetry of the photonic crystal. I can't let that happen.
Therefore, it was impossible to induce a large band structure change.

As described above, in the conventional photonic crystal, even if it has an active function, it is limited to a selective operation of expressing or erasing the function itself as a photonic crystal, or switching. However, the dimension of the photonic crystal that can realize the above is limited or the controllable range is limited. In any case, in particular, in the conventional technology, the method of changing the refractive index without changing the distribution method of the different kinds of optical materials is used, and it is possible to switch the crystal structure and the periodicity itself of the photonic crystal. I ca n’t,
It was impossible to freely and dynamically change the structure of the photonic band.

On the other hand, when a band gap occurs in the photonic crystal, if a portion of the photonic crystal whose periodicity is disturbed is one-dimensionally continuous, light is confined to only that portion, and it has been impossible to realize it conventionally. It is known that it becomes a fine optical waveguide that can be sharply bent (At
tila Mekis et al, Phys. Rev. Lett. 77, 3787 (1996)). If branches can be provided in such a fine waveguide so that the course of travel can be changed according to the wavelength of light, the waveguide itself becomes a demultiplexer, and integration in optical communication and optical circuits and simplification of the manufacturing process can be simplified. Therefore, it becomes an extremely useful optical function element.

However, in the above-described conventional technology, the same portion acts as a portion of the photonic crystal having disordered periodicity, that is, a waveguide, for light of any wavelength in the waveguide. The fine waveguide itself in the photonic crystal could not be used as a splitter according to the wavelength.

As described in detail above, in the related art, since the position where a portion having a different refractive index exists, in other words, the spatial refractive index change pattern is fixed in the space, the range of the band structure change is limited. was there. As a result, it has not been possible to freely and largely change the band structure dynamically in order to actively utilize the photonic crystal.

That is, conventionally, a technique for realizing an optical element using an active photonic crystal has not been known. Conventionally, no technique has been known in which a fine waveguide itself in a photonic crystal is used as a duplexer.

The present invention has been made based on the recognition of such a problem, and it is an object of the present invention to provide a novel and highly dynamic control of the band structure of a photonic crystal. Another object of the present invention is to provide an optical element which can perform the above control by changing a distribution pattern of complex refractive index or the periodicity itself. Another object of the present invention is to provide a novel duplexer using a waveguide inside.

[0019]

According to a first aspect of the present invention, there is provided an optical device comprising at least a second optical medium and a third optical medium in a first optical medium. A medium having a structure periodically arranged at intervals on the order of the wavelength of the incident light, and changing the external field conditions applied to the structure to change the first to third, that is, the first, second, and third conditions. The relative relationship between the refractive indices of the third optical medium is changed so that the periodicity of the spatial distribution of the refractive index formed in the structure can be changed.

Here, "the wavelength order of the incident light" means an interval on the order of the wavelength of the light to be incident on the optical element in order to perform an operation such as modulation, switching, and waveguide. More than tens of times the wavelength of
An interval that is not a significantly different interval, such as 1/0 or less.

More specifically, the optical device of the present invention is composed of three or more types of optical media, and has a one-dimensional, two-dimensional, or three-dimensional structure in which each optical medium is periodically arranged. The optical material and the temperature or external field conditions are set so that the refractive index of at least two optical media is different with respect to the frequency of the incident light, and the electric or magnetic field or pressure applied to the structure is The structure may be exposed to or applied light to the structure, or to a change in the electric field, magnetic field, or pressure applied to the structure, a change in the intensity or wavelength of light irradiation, or a change in the temperature of the structure. The combination of optical media with a larger difference in the refractive index changes at the frequency of the light incident on the inside, or a new site with a different refractive index from the surroundings appears periodically That is, the frequency region in which the incident light is affected by taking a new periodic structure after the change, or by changing the relative ratio of the periodic peak of the refractive index generated in the structure by each medium. Is characterized by having a structure in which a new band structure appears.

According to an embodiment of the above-described optical element, as described in claim 2, the first structure is such that, under the first external field condition, the first structure is used for the light of a predetermined wavelength. The refractive index of the optical medium is substantially equal to the refractive index of the third optical medium, and the refractive index of the first optical medium and the refractive index of the second optical medium are substantially different. The light of the predetermined wavelength is modulated by the periodic arrangement of the second optical medium, and in a second external field condition different from the first external field condition, the first wavelength of the light of the predetermined wavelength is changed. The refractive index of the optical medium is substantially equal to the refractive index of the second optical medium, and the refractive index of the first optical medium and the refractive index of the third optical medium are substantially different. Modulating the light of the predetermined wavelength by a periodic arrangement of the third optical medium; And it features.

More specifically, a structure having a periodic structure is composed of three types of optical media, and the first, second, and third optical media are used as first, second, and third optical media, respectively. Assuming that the refractive index of the third optical medium is the first, second, and third refractive indexes, respectively, the distribution of the first, second, and third optical media in the structure has a periodic structure. The refractive index at the frequency of light incident on the optical element is the first and third.
And the first medium and the second medium are substantially the same, that is, the difference between the first and second refractive indexes is larger than the difference between the first and third refractive indexes, and the incident light is modulated in the structure. The periodic structure of the refractive index is determined mainly by the periodic distribution of the second medium, and an electric field, a magnetic field, or a pressure is applied to the structure, or the structure is irradiated with light or the structure is irradiated with light. Electric and magnetic fields applied to the body,
Due to a change in pressure, a change in the intensity or wavelength of light irradiation, or a change in the temperature of the structure, the refractive indices at the above-mentioned frequencies are substantially equal in the first and second media and different in the first and third media. , Ie, the first and third
Is larger than the difference between the first and second refractive indices, and the periodic structure of the refractive index in which incident light is modulated in the structure is determined mainly by the periodic distribution of the third medium. , And a new band structure appears in the frequency region where the incident light is concerned.

A third optical element according to the present invention is a third optical element.
As described in above, a first optical medium, a second optical medium periodically arranged in the first optical medium, and a second optical medium formed in the first optical medium And a third optical medium arranged by replacing a continuous part of the periodic structure to be formed. The complex refractive index of the second optical medium is substantially different from the complex refractive index of the third optical medium with respect to the light, and the portion replaced by the third optical medium is light of the predetermined wavelength. Functioning as a waveguide, and in a second external field condition different from the first external field condition, the complex refractive index of the second optical medium and the third And the complex refractive index of the optical medium is substantially equal to that of the third optical medium. Said portion which is substituted is characterized in that it does not function as a waveguide for light of said predetermined wavelength.

More specifically, a two-dimensional or three-dimensional optical system comprising two or more types of optical media having different complex refractive indices, wherein portions composed of the same type of optical medium are periodically arranged. Of the periodic structure of this structure is present one-dimensionally in the structure,
In a structure in which a portion where the periodic structure is disturbed functions as an optical waveguide, when three or more types of optical media are used, and three of the optical media are first, second, and third optical media, respectively, When the first, second, and third complex refractive indices in the vicinity of the frequency ν of light incident on the optical waveguide are set to first, second, and third complex refractive indices, respectively, the first medium This optical element has a two-dimensional or three-dimensional periodic structure of the second medium, and a part of the two-dimensional or three-dimensional periodic structure of the second medium is replaced by a one-dimensionally connected third medium. Where the first complex refractive index and the second complex refractive index, and the second complex refractive index and the third complex refractive index are different from each other in the vicinity of the frequency of light incident on the portion, and are replaced by a third medium Is a structure that functions as an optical waveguide for incident light, and the structure Applying an electric field, magnetic field, or pressure to the structure, irradiating the structure with light, or changing the electric field, magnetic field, or pressure applied to the structure, or changing the intensity or wavelength of light irradiation, or the structure The first temperature change near the frequency ν
And the second complex refractive index are different, the second and third complex refractive indices become substantially equal, and the portion replaced by the third medium does not act as disturbance of the periodic structure with respect to the incident light, Since a portion functioning as an optical waveguide disappears, a waveguide having a switching function is provided.

Further, the fourth optical element of the present invention is characterized in that:
As described in above, a first optical medium, a second optical medium periodically arranged in the first optical medium, and a second optical medium formed in the first optical medium A third optical medium arranged by replacing the continuous first portion of the periodic structure to be formed, and a periodic structure to be formed by the second optical medium in the first optical medium. The fourth optical medium arranged by replacing the continuous second portion of the second optical medium, and the third continuous optical structure of the periodic structure to be formed by the second optical medium in the first optical medium. A structure having a portion where the periodicity of the second optical medium is disturbed in a portion of the first optical medium, wherein the first portion and the second portion are connected to the third portion, respectively. An optical element having a predetermined wavelength under the first external field condition. In contrast, the complex refractive index of the first optical medium, the complex refractive index of the second optical medium, and the complex refractive index of the third optical medium are substantially different from each other, and the complex refractive index of the second optical medium is The complex refractive index and the complex refractive index of the fourth optical medium are substantially equal, and the first portion and the third portion function as a waveguide for light of the predetermined wavelength, and Under a second external field condition different from the first external field condition, the complex refractive index of the first optical medium, the complex refractive index of the second optical medium, and the fourth And the complex refractive index of the second optical medium is substantially equal to the complex refractive index of the second optical medium, and the complex refractive index of the third optical medium is substantially equal to the complex refractive index of the third optical medium. The third portion functions as a waveguide for the light having the predetermined wavelength, thereby providing the third portion. Wherein the predetermined wavelength of light incident on the portion of the branch target and the first portion second
It can be switched to any one of the parts.

More specifically, a two-dimensional or three-dimensional optical system comprising two or more types of optical media having different complex refractive indices, wherein portions composed of the same type of optical medium are periodically arranged. Of the periodic structure of this structure is present one-dimensionally in the structure,
In a structure in which a portion where the periodic structure is disturbed functions as an optical waveguide, when four or more types of optical media are used and the first, second, third, and fourth optical media are used, respectively, The complex refractive indices of the first to fourth media in the vicinity of the frequency of light to be incident on the wave path are first and fourth, respectively.
When the second, third, and fourth complex refractive indexes are used, the first medium has a two-dimensional or three-dimensional periodic structure of the second medium, and has a two-dimensional or three-dimensional period of the second medium. A part of the structure is replaced by a one-dimensionally connected third medium to form a first part, and another part is replaced by a one-dimensionally connected fourth medium to form a second part. The third part is formed by the disorder of the periodic structure of the second medium that is formed and is connected to another part in a one-dimensional manner.
The first part and the second part are connected, and the first complex refractive index and the second complex refractive index are set near the frequency of light incident on the optical element.
, The second complex refractive index and the third complex refractive index are respectively different, the second complex refractive index is substantially equal to the fourth complex refractive index, and the third and first portions A structure that acts as an optical waveguide and applies an electric or magnetic field or pressure to the structure, or irradiates the structure with light, or an electric or magnetic field applied to the structure.
Due to a change in pressure, a change in the state of light irradiation, or a change in temperature of the structure, the first and second complex refractive indexes and the second and fourth complex refractive indexes near the frequency ν are different, The second and third complex refractive indices become substantially equal, and the first portion does not function as a disturbance of the periodic structure with respect to the incident light and does not function as an optical waveguide. Since it functions as a wave path, it is possible to switch the branching destination or the destination of the light incident on the third part between the first part and the second part.

On the other hand, the duplexer according to the present invention comprises a first optical medium, a second optical medium periodically arranged in the first optical medium, and the second optical medium in the first optical medium. A third optical medium which is arranged by replacing the continuous first portion of the periodic structure to be formed by the second optical medium;
A fourth optical medium arranged in the first optical medium by replacing a continuous second portion of a periodic structure to be formed by the second optical medium, and the first optical medium A portion in which periodicity of the second optical medium is generated in a continuous third portion of the periodic structure to be formed by the second optical medium; A duplexer having a structure in which a portion and the second portion are connected to the third portion, respectively, and for light of a first wavelength, the light of the first optical medium The complex refractive index, the complex refractive index of the second optical medium, and the complex refractive index of the third optical medium are substantially different from each other, and the complex refractive index of the second optical medium and the complex refractive index of the fourth optical medium are different. Are substantially equal to each other, and the first portion and the third
Functions as a waveguide for light of the first wavelength, and for light of a second wavelength different from the first wavelength, the complex refractive index of the first optical medium The complex refractive index of the second optical medium and the complex refractive index of the fourth optical medium are substantially different from each other, and the complex refractive index of the second optical medium and the complex refractive index of the third optical medium Are substantially equal, and the second part and the third part
By functioning as a waveguide for light with a wavelength of
The first wavelength incident on the third portion and the second wavelength
The light having the wavelength of (a) travels to one of the first part and the second part according to the wavelength.

More specifically, a two-dimensional or three-dimensional structure comprising two or more types of optical media having different complex refractive indices, wherein portions composed of the same type of optical medium are periodically arranged. Having a structure, and the disorder of the periodic structure of the structure exists one-dimensionally in the structure,
In a structure in which a portion where the periodic structure is disturbed functions as an optical waveguide, when four or more types of optical media are used and the first, second, third, and fourth optical media are used, respectively, The frequency of the two lights entering the wave path is
And the second frequency, the complex refractive indices of the first to fourth media near the first frequency are defined as first, second, third, and fourth complex refractive indices, respectively. , Second
When the complex refractive indices of the first to fourth media in the vicinity of the frequency of are respectively set to the fifth, sixth, seventh, and eighth complex refractive indices, 2 It has a one-dimensional or three-dimensional periodic structure, and a part of the two-dimensional or three-dimensional periodic structure of the second medium is replaced by a one-dimensionally connected third medium to form a first part. Is replaced by a one-dimensionally connected fourth medium to form a second part, and another part is formed by a one-dimensionally connected periodic structure disorder to form a third part, When the first portion and the second portion are connected to the third portion, the first complex refractive index and the second complex refractive index near the first frequency of light incident on the optical element. , The second complex refractive index and the third complex refractive index are different from each other, and the second complex refractive index and the fourth complex refractive index are different. The third and first portions function as optical waveguides for incident light, and have a fifth complex refractive index, a sixth complex refractive index, and a sixth complex refractive index near the second frequency. The eighth complex refractive index is different, the sixth complex refractive index is substantially equal to the seventh complex refractive index, and the third and second complex refractive indexes are different.
Works as an optical waveguide for incident light,
The light having the first frequency and the second frequency incident on the portion travels to the first portion and the second portion, respectively, according to the frequency, and the waveguide itself can function as a duplexer. it can.

In the present invention, the refractive index of the controlled light, ie, the frequency (wavelength) of the incident light when functioning as an optical element (a region of the frequency having a certain spread when the incident light is not monochromatic light) is used. We note that the spatial distribution determines the response of the photonic crystal to the incident light, and is independent of the refractive index distribution in other wavelength ranges.

In particular, the active optical device according to the present invention utilizes a plurality of optical media whose refractive index changes according to an external field. When fabricating a photonic crystal from such an optical material, under certain external field conditions, the refractive indices of two of the plurality of optical media are made equal or nearly equal. Then, the periodic distribution of the refractive index sensed by the light becomes a distribution pattern of an optical medium other than the two optical media having the same refractive index.

Further, under different external field conditions, the refractive indexes of the other two optical media are made equal. Also in this case, the light in the optical element feels a distribution pattern of an optical medium other than the optical medium having the same refractive index under the condition.

By setting the distribution pattern sensed by light under these two conditions to a desired crystal structure, lattice point shape, and period, it is only necessary to change the external field conditions between two greatly different photonic band structures. Can be switched dynamically.

A switchable waveguide in a photonic crystal according to the present invention, according to the same principles as described above,
It operates by changing the position of the disorder of the periodicity of the refractive index in the photonic crystal that is felt by changing the condition of the external field.

Further, the duplexer according to the present invention utilizes the fact that the refractive index of the optical medium changes depending on the frequency (wavelength) of the incident light instead of changing the condition of the external field.
That is, the photonic crystal and the waveguide are configured with a combination of optical media such that the position at which light is perceived as disorder in the periodicity of the refractive index in the photonic crystal varies depending on the wavelength, and functions as a duplexer.

[0036]

Embodiments of the present invention will be described below with reference to the drawings.

A medium whose refractive index changes spatially and periodically in the order of the wavelength of light is called a "photonic crystal".
Shows specific optical properties. This is because in such a structure, light senses the periodicity of the refractive index and exhibits a band structure. Similar to the band gap in the energy of electrons in a semiconductor, a photonic band gap, which is a frequency region that blocks light propagation, can be generated in a photonic band structure. With these photonic band structures and photonic band gaps, a large wavelength dispersion and anisotropy, a waveguide with a sharp bend angle that can be integrated in a narrow space, and the like can be realized.

What determines this band structure is the spatial distribution of the refractive index. In particular, the band structure in the wavelength region (frequency region) of the incident light, which determines the response of the photonic crystal to the incident light, is determined by the refractive index distribution in the wavelength region of the incident light.

In the present invention, at least two types of optical media are used to construct a photonic crystal. The optical media are arranged periodically. Here, the “optical medium” is a concept including air in the case of a dielectric three-dimensional periodic structure constructed in a vacuum or air, or a space such as a vacuum space, a gas, a liquid, or the like. In the following description, when the external field condition is A, the refractive index of the i-th optical medium with respect to light having a frequency ν is n
_i (ν, A). "External field conditions" refer to conditions of electric field, magnetic field, and pressure applied to the photonic crystal, or conditions such as the intensity, wavelength, and polarization direction of light applied to the photonic crystal, or the temperature of the photonic crystal. I do.

First, let us consider a case where the N types of optical media constituting the photonic crystal have different refractive indices under the external field condition A ₁ .

FIG. 1 is a conceptual diagram exemplifying a case where the three types of optical media have different refractive indexes. That is, FIG. 1 shows a structure in which the second optical medium 2 and the third optical medium 3 are periodically arranged in the first optical medium 1.
The first to third optical media have different refractive indices from each other. This condition can be expressed by the following equation. _{n i (ν 1, A 1} ) ≠ n j (ν 1, A 1) (i ≠ j) , where, n _i represents the refractive index of the optical medium of the j. In this case, the band structure near the frequency ν ₁ of the incident light is
The periodic structure of the refractive index determined by the spatial distribution of the (N-1) types of optical media and the refractive index of all the N types of optical media. FIG. 1 corresponds to the case where N = 3.

Next, by changing the external field condition to A ₂ , the refractive indices of two of the N types of optical media are made equal.

FIG. 2 is a conceptual diagram illustrating this state. For example, assuming that the two materials having the same refractive index are the k-th and l-th optical media (k <l), a state represented by the following equation is obtained. n _k (ν ₁ , A ₂ ) = n _l (ν ₁ , A ₂ ) This is because the external field is in the state of A ₂ , and the k-th and l-th optics at the frequency ν ₁ of the incident light are obtained. This means that the refractive indices of the media have become equal. Here, it is assumed that the k-th and l-th optical media are in contact with each other. In this state,
The spatial distribution of the l-th to (k−1) -th optical media, and the k-th and l-th
The band structure is determined by the spatial distribution of the combined optical medium, the spatial distribution of the (k + 1) th to (1-1) th optical medium, the spatial distribution of the (l + 1) to Nth optical medium, and their refractive indexes. However once the spatial distribution of N-1 type of optical medium, so determined the spatial distribution of the remaining one type of optical medium, eventually N-1 type of medium exhibiting N-1 different kinds of refractive index in [nu ₁ (first k and the first optical medium are 1
The band structure is determined by the spatial distribution of the N-2 types of optical media and the refractive index values of the N-1 types. FIG. 2 shows the situation when N = 3.

Next, as shown in FIG. 3, by changing the external field condition to A ₃ , the m-th and n-th optical media (m <n) which are combinations of the k-th and the l-th optical media are not used. At ν ₁
It is assumed that the refractive indices at are made equal. That is, _nm (ν ₁ , A ₃ ) = n _n (ν ₁ , A ₃ ). Here, it is assumed that the m-th and n-th optical media are in contact with each other. In this state, the spatial distribution of the l-th to the (m-1) -th optical medium, the spatial distribution of the medium combining the m-th and the n-th optical medium, and the spatial distribution of the (m + 1) -th to the (n-1) -th optical medium The band structure is determined by the spatial distribution of the n + 1 to N-th optical media and their refractive indexes. The situation is as illustrated in FIG.

As shown in FIGS. 1 to 3, the conditions of the external field are set between A ₁ , A ₂ and A ₃ , that is, between A ₁ and A ₂ ,
By switching between ₂ and A ₃ or between A ₁ and A ₃ , it is possible to switch the spatial arrangement pattern of the refractive index distribution that determines the band structure. As a result, a larger change can be induced in the band structure of the photonic crystal with respect to incident light than when only the value of the refractive index is changed.

Here, it has been assumed that the optical media having the same refractive index are in contact with each other under the conditions A ₂ and A _3. However, even when they are not in contact, the spatial distribution pattern can be changed. An example is shown below.

FIG. 4 is a conceptual diagram exemplifying a case where the external field condition is switched from A ₁ to A ₂ in a photonic crystal comprising the first, second and third optical media. In this case, it is assumed that, in the first optical medium 1, the regions closed by the second optical medium 2 and the third optical medium 3 in space are simple cubic lattices having the same period and the same shape of lattice points. However, when the respective basic period vectors are represented by a, b, and c, the lattice points of the second and third optical media are shifted by a / 2, b / 2, and c / 2. Placing such an optical material under the condition A _1,
Since the second and third refractive indices are different, the crystal structure is as shown in FIG.
As shown in (a), a “cesium chloride type structure” is obtained.

Next, when the external field condition is changed to A ₂ , the second and third optical media become indistinguishable for incident light.
As shown in FIG. 4B, the crystal structure is equivalent to a body-centered cubic lattice structure. Thus, conditions A ₁ and A ₂
Changes the crystal structure of the photonic crystal with respect to the incident light.

Next, a structure having at least three types of optical media as constituent elements will be considered with reference to FIG. The three optical medium as a first optical medium 1, the second optical medium 2 and the third optical medium 3, the refractive index with respect to the control light [nu ₁ is assumed to satisfy the following relation. n ₁ (ν ₁ , A ₁ ) ≠ n ₂ (ν ₁ , A ₁ ) n ₂ (ν ₁ , A ₁ ) ≠ n ₃ (ν ₁ , A ₁ ) In the first medium, the second medium Construct a three-dimensional periodic structure. In that case, it is desirable that the photonic crystal generated by the periodic structure opens a band gap in a wide direction at the incident light frequency ν ₁ , and it is particularly desirable to form a diamond structure in which the band gap opens in all directions.

As shown in FIG. 5A, a part of the second medium constituting the periodic structure is converted into a one-dimensionally connected third medium.
Replace with the optical medium. Then, the light is confined in the one-dimensionally connected portion where the periodicity of the photonic crystal is broken, and the light cannot propagate in any direction other than the direction in which the portions are connected. Work as an optical waveguide.

Next, the external field condition is changed to A ₂ . Under this condition, the relationship between the refractive indices of the optical medium satisfies the following relationship. n ₁ (ν ₁ , A ₂ ) ≠ n ₂ (ν ₁ , A ₂ ) n ₂ (ν ₁ , A ₂ ) = n ₃ (ν ₁ , A ₂ ) In this case, the second and third optical media are Becomes equivalent for light having a frequency ν ₁ , and the loss of periodicity in the photonic crystal disappears. That is, as shown in FIG. 5B, the waveguide disappears. By switching the conditions A ₁ and A ₂ in this manner, the function as the waveguide is turned ON / OFF.
can do.

Next, referring to FIG.
Consider a structure having a kind of optical medium as a component. So
The four types of optical media are a first optical medium 1 and a second optical medium.
, The third optical medium 3 and the fourth optical medium 4,
Case A₁ Controlled light ν at ₁ The refractive index for
Re₁ (Ν₁ , A₁ ), N_Two (Ν₁ , A₁ ), N_Three (Ν
₁ , A₁ ), N_Four (Ν₁ , A₁ ). Furthermore, it
It is assumed that each refractive index satisfies the following relationship. n₁ (Ν₁ , A₁ ) ≠ n_Two (Ν₁ , A₁ ) N_Two (Ν₁ , A₁ ) ≠ n_Three (Ν₁ , A₁ ) N_Two (Ν₁ , A₁ ) ≠ n_Four (Ν₁ , A₁ Here, as illustrated in FIG. 6, the second medium is provided in the first medium.
It is assumed that a three-dimensional periodic structure is formed by a medium. This
Also, the photonic crystal generated by the periodic structure
Is the incident light frequency ν₁ Bandgi for wide direction at
It is desirable to open the gap, especially in all directions
It is desirable to form a diamond structure in which the gap opens.
No. FIG. 6 shows a part of the second medium having the periodic structure.
As illustrated, the third optical medium that is connected in a one-dimensional manner is placed.
Change. Then, the periodicity of the photonic crystal collapsed
The one-dimensionally connected portion is the same as that described above with reference to FIG.
As in the case, it becomes a waveguide. That is, the third optical medium is
Encloses light that is going to propagate in directions other than
Functions as a wave path. This is called the “first waveguide”.
And

As shown in FIG. 6, when another part is replaced by a one-dimensionally connected fourth optical medium, that part also functions as a waveguide. This is called "
Waveguide ".

Further, as shown in FIG. 6, when a portion having a periodicity that is one-dimensionally connected to another part is created,
That portion also becomes a waveguide. The part is called "third waveguide"
I will call it. These three waveguides are connected to form a branched waveguide.

FIG. 7 is a conceptual diagram showing the operation of the optical device formed as described above.

[0056] First, as shown in FIG. 6 (a), in the external field condition A _1, acts as a first, second and third one of the waveguides also waveguide with respect to the incident light. Therefore, for example, light incident from the left end of the third waveguide branches to the first and second waveguides, respectively.

Next, assume the state shown in FIG. 7B. That is, the external field condition A such that the refractive index satisfies the following relationship:
_{Assume 2} . n ₁ (ν ₁ , A ₂ ) ≠ n ₂ (ν ₁ , A ₂ ) n ₂ (ν ₁ , A ₂ ) ≠ n ₃ (ν ₁ , A ₂ ) n ₂ (ν ₁ , A ₂ ) = n ₄ (Ν ₁ , A ₂ ) Then, since n ₂ (ν ₁ , A ₂ ) = n ₄ (ν ₁ , A ₂ ), the part that was the second waveguide was a part where the periodicity was disturbed. And no longer functions as a waveguide. That is, in the external field condition A _2, the light that has propagated through the third waveguide passes to only the first waveguide, it does not proceed to the second waveguide.

Next, assume the state shown in FIG. That is, the external field condition A is set so that the refractive index satisfies the following relationship:
Change to ₃ . n ₁ (ν ₁ , A ₃ ) ≠ n ₂ (ν ₁ , A ₃ ) n ₂ (ν ₁ , A ₃ ) = n ₃ (ν ₁ , A ₃ ) n ₂ (ν ₁ , A ₃ ) ≠ n ₄ (Ν ₁ , A ₃ ) Then, n ₂ (ν ₁ , A ₃ ) = n ₃ (ν ₁ , A ₃ )
₃ ), the portion that was the first waveguide no longer functions as a waveguide. That light in propagating the third waveguide condition A ₃ proceeds to only the second waveguide, does not proceed to the first waveguide.

As described above, the conditions are A ₁ , A
By switching between A ₂ and A ₃ , it is possible to switch the way of branching light traveling in the optical waveguide.

Next, with reference to FIG. 8, a description will be given of the operating principle of the duplexer provided in the waveguide in which the way of branching differs depending on the wavelength of the incident light.

As in the waveguide illustrated in FIG.
Assuming a structure having various types of optical media as components,
The four types of optical media are referred to as first, second, third, and fourth optical media.
An optical medium. In addition, the external field conditions of these optical media
A₁At the incident light frequency ν₁And ν_TwoRefraction for
Rate n₁ (Ν₁ , A₁ ), N_Two (Ν₁ , A
₁ ), N_Three (Ν₁ , A₁ ), N_Four (Ν₁ , A₁ ) And
And n₁ (Ν_Two , A₁ ), N_Two (Ν_Two , A₁ ), N_Three 
(Ν_Two , A₁ ), N_Four (Ν_Two , A₁ ).

It is assumed that these refractive indices satisfy the following relationship. n ₁ (ν ₁ , A ₁ ) ≠ n ₂ (ν ₁ , A ₁ ) n ₂ (ν ₁ , A ₁ ) ≠ n ₃ (ν ₁ , A ₁ ) n ₂ (ν ₁ , A ₁ ) = n ₄ (Ν ₁ , A ₁ ) n ₁ (ν ₂ , A ₁ ) ≠ n ₂ (ν ₂ , A ₁ ) n ₂ (ν ₂ , A ₁ ) = n ₃ (ν ₂ , A ₁ ) n ₂ (ν ₂ , A ₁ ) ≠ n ₄ (ν ₂ , A ₁ ) FIGS. 8A and 8B are conceptual diagrams showing an optical element having a branched waveguide formed by these optical media. That is, first, a three-dimensional periodic structure is formed by the second medium in the first medium. Also in this case, it is desirable that the photonic crystal generated by the periodic structure opens a band gap in a wide direction at incident light frequencies ν ₁ and ν ₂ , and in particular, to form a diamond structure in which the band gap opens in all directions. desirable.

A part of the second medium having the periodic structure is replaced by a one-dimensionally connected third optical medium as illustrated in FIG. 8A. Then, n ₂ (ν ₁ , A ₁ )
Since ≠ n ₃ (ν ₁ , A ₁ ), for light having the frequency ν ₁ , that part becomes a part where the periodicity of the photonic crystal is broken and propagates in a direction other than the direction in which the third optical medium continues. The light having the frequency ν ₁ to be confined functions as an optical waveguide. However, for light of frequency ν ₂ , n ₂
Since (ν ₂ , A ₁ ) = n ₃ (ν ₂ , A ₁ ),
It does not become a part where periodicity is disturbed, and does not function as a waveguide. This portion will be referred to as a “first waveguide”.

Another part is illustrated in FIG.
As in the fourth optical medium, which is also one-dimensionally connected.
In other words, the site is n_Two (Ν₁ , A₁ ) = N_Four (Ν
₁ , A ₁ ), The frequency ν₁ For the light of
It does not become a part where periodicity is disturbed and does not function as a waveguide.
No. But the frequency ν_Two For light of n_Two (Ν_Two , A
₁ ) ≠ n_Four (Ν_Two , A₁ ), The periodicity
And functions as a waveguide. This part is
Two waveguides ".

As shown in FIG. 8 (a), the light having the frequency ν _{1 and} the light ν
The disorder of the periodicity with respect to the _second light is formed, which is referred to as a “third waveguide”. The first and second waveguides are connected to the third waveguide.

As shown in FIG. 8B, when light of frequency ν ₁ and light of frequency ν ₂ are incident from the left end of the third waveguide portion of this waveguide, light of frequency ν ₁ is emitted. Goes to the portion consisting of the waveguide 1 in the branch, but does not go to the portion consisting of the waveguide 2. Conversely, the light having the frequency ν ₂ does not travel to the portion consisting of the waveguide 1, but travels to the portion consisting of the waveguide 2. In this way, it becomes possible to split the light of ν ₁ and ν ₂ propagating through the third waveguide according to the frequency (wavelength).

In the description of the optical device having a waveguide described above with reference to FIGS. 5 to 8, a one-dimensional waveguide provided in a three-dimensional photonic crystal has been described. However, the present invention is not limited to a three-dimensional photonic crystal. That is, the present invention can be applied to a waveguide using a disorder of a one-dimensional periodic structure in a photonic crystal having a two-dimensional periodic structure.

In addition, the active switching of the photonic band structure or the switching in the waveguide described above with reference to FIGS. 1 to 8 does not use a mere change in the refractive index due to an external field, but uses the refractive index of a substance. By utilizing the difference of the external field, by applying an external field, the refractive index of two optical materials among a plurality of optical materials constituting a photonic crystal or an optical element using the same is changed to a certain wavelength. The fact that it is possible to make them equal or close to each other is used.

FIG. 9 is a graph illustrating the dependence of the refractive index on the external field for three types of optical media. As the external field, an electric field, a magnetic field, light, pressure, temperature and the like can be used. The main types of these external fields and the main mechanisms that can be used to switch the photonic band structure of the present invention when a change in the refractive index is induced by adding them are listed below.

Regarding the electric field, Stark shift,
Franz Keldysh effect, Bockels effect,
A Kerr effect, a change in refractive index due to a change in orientation (particularly effective for polarized light), and the like can be used.

Regarding the magnetic field, a change in the refractive index caused by a shift in resonance energy accompanying level splitting by the magnetic field;
The Cotton-Mouton effect can be used.

Regarding light, the optical Stark effect, the change in the refractive index due to the movement of the population due to light excitation (absorption saturation), and the change in the refractive index due to quantum interference due to light irradiation (Electromagnetically Induced Transp.
arity), a refractive index change due to photoisomerization, a refractive index change due to a structural change due to light irradiation, a refractive index change due to photoionization, and the like can be used.

Regarding the pressure, the piezo-reflection effect (piez
oreflectance effect).

As for the temperature, it is possible to use a refractive index change due to a band shift of an electronic structure due to a temperature change, a refractive index change due to isomerization due to a temperature change, and a refractive index change due to a structural change due to a temperature change.

Further, even if any two or more of the above-mentioned external fields are combined, a change in the refractive index can be effectively induced. Further, in the present invention, by using exactly the same mechanism as described above, if a photonic crystal is made of a substance that uses a specific polarized light as the controlled light and induces a change in the refractive index with respect to the polarized light, the specific polarized light can be obtained. In contrast, dynamic switching of the photonic band structure, switching of the waveguide, and demultiplexing are possible.

[0076]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 In order to fabricate an optical device as one example of the present invention, first, a porous material of silica (SiO ₂ ) serving as a framework of a photonic crystal was prepared. The size of this porous body is 1 mm × 1 mm × 1 mm, and the porosity is 9
0% or more, the average pore diameter is 30 nm, and 1.0
Indicates a refractive index of 15 to 1.055.

This porous silica was immersed in an ethanol solution of a ruthenium complex to impregnate the ruthenium complex.

FIG. 10 shows the structural formula of the ruthenium complex. It was immersed in an ethanol solution for about 1 hour, during which heating and refluxing were performed to adsorb the ruthenium complex on the inner wall of the porous silica. Then, the silica porous body is washed with ethanol,
Unadsorbed ruthenium complex was washed out.

Next, a laser beam of the fourth harmonic (wavelength: 266 nm) of the Q-switched YAG laser was condensed by a lens to a spot diameter of about 300 nm, and was irradiated on the porous silica thus treated. At that time, the mirror was operated by a driving system using a piezo element to focus on the inside of the porous silica material, and three-dimensional patterning was performed at the focal point while sequentially changing the position of the focal point. At the focus, the ruthenium complex was decomposed by intense ultraviolet light. In patterning, the remaining portion of the ruthenium complex without being decomposed forms a face-centered cubic lattice with a lattice constant of 700 nm.

FIG. 11 is a conceptual diagram showing the distribution of a ruthenium complex in a porous silica material. As shown in the figure, the ruthenium complex is formed so as to form a face-centered cubic lattice. In addition, as shown in FIG. 11, the portion of each lattice point of the face-centered cubic lattice that was not irradiated with strong ultraviolet rays was a rugby ball type having a major axis of about 350 nm and a minor axis of about 300 nm. Further, the axis of the major axis is directed to the direction of the closest lattice point. By doing this,
The undecomposed ruthenium complex remained only in the rugby ball-shaped portion forming the face-centered cubic lattice. In order to remove the decomposition products of the ruthenium complex inside the porous silica, washing was performed using ethanol and methanol.

Next, this silica porous material was mixed with 4-epoxymorphino-2,5-dibutyroxybenzenediazoniuoufukka salt as a photoacid generator in Celoxide 2021 (trade name, manufactured by Daicel Chemical Industries, Ltd.) as an epoxy resin. % Of the liquid and impregnated with the liquid.

Thereafter, a laser beam having a wavelength of 407 nm is generated by a dye laser excited by an excimer laser,
Using a device similar to that used for patterning with light of 66 nm, the inside of the porous silica impregnated with epoxy resin was focused, and its position was sequentially changed to obtain a face-centered cubic lattice having a lattice constant of 1.4 μm. At the position where the wavelength 40 is formed.
Irradiation with intense light of 7 nm was performed. At each lattice point, the part to be irradiated with strong light having a wavelength of 407 nm is formed as a rugby ball type having a major axis of about 450 nm and a minor axis of about 400 nm, and the axis of the major axis is oriented in the direction of the nearest lattice point. I turned to.

In patterning with light having a wavelength of 407 nm, a pattern was formed at a position where the center did not overlap with the pattern formed with light having a wavelength of 266 nm by alignment with a marker formed on a porous silica material.
Further, the porous silica was heated at 60 ° C. for 5 hours. By doing so, a cured portion of the epoxy resin was formed only in a rugby ball-shaped portion forming a face-centered cubic lattice having a lattice constant of 1.4 μm. Thereafter, the porous silica was washed with acetone and methanol to remove the uncured resin and the acid generator.

Next, the porous silica thus treated was immersed in methyl methacrylate containing 10% by weight of a dye (manufactured by Lambda Physics Co., Ltd., IR26), and impregnated with methyl methacrylate. Thereafter, when the entire porous silica was irradiated with a laser beam having a wavelength of 500 nm from an excimer-excited dye laser, only methyl methacrylate that permeated the ruthenium complex in the porous silica was polymerized by the catalytic action of the ruthenium complex. did. After photopolymerization, the porous silica was washed with acetone to remove unpolymerized methyl methacrylate. As a result, rugby ball-type polymethyl methacrylate was formed at a portion where a face-centered cubic lattice having a lattice constant of 700 nm was formed.

Next, the ruthenium complex was again adsorbed to the portion of the porous silica which was not occupied by the epoxy resin and polymethyl methacrylate with an ethanol solution, and the unadsorbed portion was removed by washing, and further 2 wt. % Of the dye (Lambda Physic, IR26) containing methyl methacrylate. Thereafter, methyl methacrylate was polymerized by irradiation with a laser beam having a wavelength of 500 nm.

FIG. 12 is a conceptual diagram showing the structure of the photonic crystal thus created. As shown in the figure, the photonic crystal of this example has a polymethyl methacrylate containing 2% by weight of a dye as a matrix, and the matrix contains 10% by weight of a rugby ball-shaped dye. A face-centered cubic lattice with a lattice constant of 700 nm made of methyl methacrylate and a face-centered cubic lattice with a lattice constant of 1.4 μm made of an epoxy resin are formed.

This photonic crystal has a wavelength of 100
When the infrared reflection spectrum at around 0 nm was measured, a large reflection peak appeared just at around 1000 nm.
This is because, in the wavelength region around 1000 nm, polymethyl methacrylate in which 2% by weight of a dye is dispersed, and polymethyl methacrylate in which 10% by weight of a dye is dispersed and 2% by weight of a dye are determined from the difference in the refractive index of the epoxy resin. The difference in the refractive index of the dispersed polymethyl methacrylate is larger,
This is mainly because a photonic band was formed by a spatial pattern of polymethyl methacrylate in which 10% by weight of dyes were dispersed in a face-centered cubic pattern having a lattice constant of 700 nm. As a result, a region having a particularly high reflectance is 100
It is considered that it appeared near 0 nm.

On the other hand, this photonic crystal has a wavelength of 11
While irradiating with 00 nm infrared light, the reflection spectrum at around 1000 nm was measured again.

FIG. 13 is a graph showing a reflection spectrum around 1000 nm in the irradiation / non-irradiation state of infrared light having a wavelength of 1100 nm. As can be seen from FIG.
In the state irradiated with the infrared light of 00 nm, 1000
The large reflection peak near nm disappeared. This is due to the fact that absorption saturation occurs at the site where the dye is dispersed by light irradiation at a wavelength of 1100 nm, and the difference in refractive index between polymethyl methacrylate in which 10% by weight of the dye is dispersed and polymethyl methacrylate in which 2% by weight of the dye is dispersed. This is probably due to the smaller size.

Further, under this condition, in the wavelength region around 1000 nm, the difference between the refractive index of polymethyl methacrylate in which 2% by weight of the dye is dispersed and the refractive index of the epoxy resin are 2% in comparison with the case of polymethyl methacrylate in which 10% by weight of the dye is dispersed. Since the difference in refractive index between polymethyl methacrylate in which a weight% dye is dispersed is larger than that of polymethyl methacrylate, the lattice constant is 1.4 μm.
It is considered that the photonic band is formed by the distribution pattern of the epoxy resin forming the face-centered cubic of m. Actually, in the near infrared region, a reflection peak is observed at around 2000 nm, which is considered to be due to a photonic band due to the distribution pattern of the epoxy resin.

As described in detail above, by forming a photonic crystal using three types of optical media, the spatial pattern of the portion forming the photonic band is switched with respect to a certain wavelength by light irradiation, and the optical response is greatly changed. I was able to.

(Example 2) A silica porous material having the same standard and size as that used in Example 1 was applied to celoxide 2021 (trade name, manufactured by Daicel Chemical Co., Ltd.) as an epoxy resin and 4- It was immersed in a liquid containing 1% of morpholino-2,5 dibutyroxybenzenediazonium boufukka salt and impregnated with the liquid. Thereafter, a laser beam having a wavelength of 407 nm was generated by a dye laser excited by an excimer laser, and focused inside the porous silica impregnated with epoxy resin using the same apparatus as that used in the patterning in Example 1. And the positions are sequentially changed, and a wavelength 4 is set at a position where a face-centered cubic lattice having a lattice constant of 1.4 μm is formed.
Intense light of 07 nm was applied. At each lattice point, the part to be irradiated with strong light having a wavelength of 407 nm is formed as a rugby ball type having a major axis of 450 nm and a minor axis of 400 nm, and the axis of the major axis is directed to the direction of the nearest lattice point. I made it. After forming 10 or more lattice points in the porous silica material, the porous silica material was heated at 60 ° C. for 5 hours. Thereafter, the porous silica was washed with acetone and methanol to remove the uncured resin and the acid generator.

Next, 10% by weight of a dye (manufactured by Lambda Physics Co., IR26) and 1% by weight of 4-morpholino 2,
The porous silica thus treated was immersed in an epoxy resin celloxide 2021 (manufactured by Daicel Chemical Co., Ltd.) containing 5 dibutyroxybenzenediazonium boufukka salt, and impregnated with an epoxy resin containing a dye. After that, the sample was set again on the patterning apparatus using a laser beam having a wavelength of 407 nm by precise alignment using the marker formed on the porous silica material, and the uppermost layer was formed on the uppermost layer of the previously formed face-centered cubic lattice. In a coordinated manner, light is sequentially radiated to positions corresponding to one-dimensionally connected one-line lattice points, and at each lattice point, a portion irradiated with light having a wavelength of 407 nm has a major axis of 450 nm and a minor axis of 450 nm. It was made to be a rugby ball type of 400 nm, and the axis of its major axis was made to coincide with the direction of the major axis of the lattice point forming the lower face-centered cubic lattice.

FIG. 14 is a conceptual diagram showing the structure obtained in this way.

After one row of lattice points containing the dye were formed, the porous silica was heated at 60 ° C. for 5 hours. Thereafter, the porous silica was washed with acetone and methanol to remove the uncured resin and the acid generator.

Next, 1% by weight of 4-morpholino-2,5
The porous silica subjected to the above treatment was immersed in an epoxy resin celloxide 2021 (manufactured by Daicel Chemical Industries, Ltd.) containing dibutyroxybenzenediazonium boufukka salt to impregnate the epoxy resin.

Thereafter, the sample was again adjusted to a wavelength of 407 by precise positioning using a marker formed on the porous silica material.
set in the patterning device by laser light of nm,
The lattice point that forms the face-centered cubic lattice on top of the previously formed face-centered cubic lattice and the epoxy resin containing a row of dyes on top By irradiation, 10 or more layers were formed. At that time, at each lattice point, the part irradiated with strong 407 nm light is made to be a rugby ball type with a long diameter of 450 nm and a short diameter of 400 nm, and the axis of the long diameter is
The direction of the major axis of the lattice point forming the lower face-centered cubic lattice was made to coincide.

Thereafter, the porous silica was heated for 5 hours while maintaining the porous silica at 60 ° C. Then, the porous silica was washed with acetone and methanol to remove the uncured resin and the acid generator.

FIG. 15 is a conceptual diagram showing an evaluation method performed on the waveguide function in the photonic crystal thus obtained.

First, as shown in FIG. 10A, a porous silica material is cut so that the end of an epoxy resin containing a one-dimensionally linked dye in a photonic crystal is exposed, and optical fibers are connected to both ends. did. This fiber has a wavelength of 100
When the laser light of 0 nm is incident, 90% of the incident light intensity is transmitted from the fiber on the opposite side across the photonic crystal.
It was observed that light with an intensity of was output. That is,
The part of epoxy resin containing one-dimensionally linked dye is
It became a part where periodicity was disturbed in the photonic crystal, and it was confirmed that it functioned as an optical waveguide.

Next, as shown in FIG. 15B, the photonic crystal was irradiated with a laser beam having a wavelength of 1100 nm,
When the intensity was changed, the output light intensity became zero at a certain intensity. This is because the refractive index of lattice points made of epoxy resin containing pigment changes due to light irradiation, and the difference in refractive index from lattice points containing no pigment disappears, leading to a one-dimensional connection of epoxy resin containing pigment. It is considered that it did not function as a wave path.

As described in detail above, according to this embodiment,
An optical waveguide exhibiting a switching function was produced by irradiating light of 1100 nm.

(Example 3) An optical element having an optical waveguide formed in a photonic crystal was manufactured using a porous silica material having the same standard and size as used in Example 2, and by the same patterning method. .

FIG. 16 is a conceptual diagram showing the structure of the photonic crystal manufactured in this embodiment. In this example, as a site having disordered periodicity, a dye having an absorption peak near 1100 nm (IR2 manufactured by Lambda Physics, Inc.)
In addition to a waveguide part consisting of lattice points formed of an epoxy resin containing 10% by weight (hereinafter referred to as “waveguide A”), a dye having an absorption peak near 850 nm (IR132, manufactured by Lambda Physics Co., Ltd.) A waveguide formed by containing epoxy resin (hereinafter, referred to as “waveguide B”) and a lattice defect caused by not forming a lattice point of epoxy resin at a place where a lattice point should be formed in a one-dimensional manner ( (Referred to as “waveguide C”). These waveguides, in a photonic crystal,
The connections were made as shown in FIG.

Of these three types of waveguides, a laser beam having a wavelength of 1000 nm guided by an optical fiber was incident from the left end of the waveguide formed by waveguide C. However, the entire photonic crystal was irradiated with a laser beam having a wavelength of 850 nm. When the output light from the ends of the waveguides A and B was measured, it was found that 80% or more of the incident laser light was output from the waveguide A. This is considered to be due to the following mechanism.

That is, under these conditions, the incident 10
The wavelength of the light of 00 nm is located on the high energy side of the absorption peak wavelength of 1100 nm with respect to the waveguide A, and is in a spectral region showing a refractive index lower than that of the epoxy resin alone. On the other hand, for the waveguide B, the absorption peak wavelength 8
It is in the spectral region where the refractive index on the low energy side of 50 nm increases. However, the waveguide B is strongly excited by the 850 nm laser light, and the refractive index has changed to a value close to that of the epoxy resin alone due to the absorption saturation. It is hard to feel. For this reason, only the waveguide A that actually acts as a waveguide is the incident light that is perceived as disorder in the periodicity of the refractive index.

Next, the wavelength 850 is applied to the entire photonic crystal.
Irradiation with laser light having a wavelength of 1100 nm was performed instead of laser light of nm. When laser output light having a wavelength of 1000 nm from the ends of the waveguides A and B was measured under these conditions, it was found that 80% or more of the incident laser light was output from the waveguide B. This is considered to be due to the following mechanism.

That is, under this condition, the incident 10
The wavelength of the light of 00 nm is located on the low energy side of the absorption peak wavelength of 850 nm for the waveguide B and is in a spectral region showing a higher refractive index than the refractive index of the epoxy resin alone, whereas for the waveguide A, Absorption peak wavelength 1
It is in the spectral region where the refractive index on the high energy side of 100 nm is low. However, the waveguide A has a wavelength of 1100 nm.
Is strongly excited by the laser light, and the refractive index is changed to a value close to that of the epoxy resin alone due to the absorption saturation, so that the incident light is hardly perceived as disorder in the periodicity of the refractive index. Therefore, what actually works as a waveguide is
Only the waveguide B which the incident light feels as disorder of the periodicity of the refractive index is obtained.

As described in detail above, according to this embodiment,
By changing the wavelength of the light irradiating the optical element, it was possible to switch the branching of the light traveling in the waveguide.

Example 4 An optical device having an optical waveguide formed in a photonic crystal was manufactured using a porous silica material having the same standard and size as that used in Example 3, and by the same patterning method. .

However, in this embodiment, as a portion having a disorder in periodicity, a lattice point formed of an epoxy resin containing 10% by weight of a dye having an absorption peak near 600 nm (Cresyl Violet, manufactured by Lambda Physics) is used. Waveguide (referred to as "Waveguide A") and a dye having an absorption peak near 450 nm (Coumarin 334, manufactured by Lambda Physics)
(Hereinafter referred to as "waveguide B"), and a waveguide formed by one-dimensionally connecting lattice defects due to the absence of epoxy resin lattice points where the lattice points should be. (Referred to as “waveguide C”), three types of waveguides were produced. These waveguides are
Connections were made in the photonic crystal in the same arrangement as in Example 3.

Of the three types of waveguides, the wavelength 70 guided by the optical fiber to the waveguide portion formed by the waveguide C.
When laser light having two wavelengths of 0 nm and 500 nm was incident and the output light from the waveguides B and C was measured, 80% or more of the incident light at 700 nm was incident from the waveguide A at 500 nm. 80% or more output from the waveguide B.

This is because for light having a wavelength of 700 nm,
It is the waveguide A that the epoxy resin containing the dye of the waveguide portion has a high refractive index unlike the other portions of the epoxy resin, and for the light having a wavelength of 500 nm, the epoxy resin containing the dye of the waveguide portion has a high refractive index. The waveguide B has a high refractive index unlike the other portions of the epoxy resin.

As described above, according to the present embodiment,
The branching direction was changed according to the wavelength, and an optical element functioning as a demultiplexer was obtained.

[0116]

As described above, according to the present invention,
By changing the external field, with respect to the refractive index of the photonic crystal or the optical waveguide provided therein, the combination of optical media whose refractive index differs more greatly at the frequency of the controlled light to be incident is changed, or a new one is obtained. The site where the refractive index differs from the surroundings appears periodically, that is, a new periodic structure is taken after the change, or the periodic ratio of the refractive index generated in the photonic crystal by each medium changes, It is possible to actively switch the response of the photonic crystal or the waveguide to the controlled light. In addition, by forming a portion having a periodic structure of the refractive index in different places depending on the wavelength of the controlled light, it is possible to configure a branching filter in which the waveguide that advances further differs depending on the wavelength in the branch.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a state of a refractive index distribution in a photonic crystal.

FIG. 2 is a conceptual diagram showing a state of a refractive index distribution in a photonic crystal.

FIG. 3 is a conceptual diagram showing a state of a refractive index distribution in a photonic crystal.

FIG. 4 is a diagram showing a state in which a cesium chloride type structure and a body-centered cubic structure are switched depending on external field conditions.

FIG. 5 is a conceptual diagram showing a state of switching of the optical waveguide.

FIG. 6 is a schematic diagram illustrating a refractive index distribution of an optical waveguide whose branching method can be switched according to conditions.

FIG. 7 is a diagram showing a state in which the direction of light propagation in the optical waveguide is switched according to conditions.

FIG. 8 is a schematic diagram illustrating a refractive index distribution of a duplexer formed by an optical waveguide in a photonic crystal.

FIG. 9 is a conceptual diagram showing how the refractive indices of a plurality of optical media depend on an external field.

FIG. 10 is a diagram showing a chemical structure of a ruthenium complex which is a catalyst for a photopolymerization reaction used in one example of the present invention.

FIG. 11 is a view showing the distribution of a ruthenium complex in a porous silica material during the production of an example of the photonic crystal of the present invention. The shadows are shown in different ways to make it easier to understand from the layer in front.

FIG. 12 is a diagram showing a structure in one embodiment of the photonic crystal of the present invention. However, only the first layer is shown.

FIG. 13 is a reflection spectrum of the photonic crystal of FIG.

FIG. 14 is a diagram showing an arrangement of an epoxy resin containing a dye during the production of an embodiment of the optical waveguide in the photonic crystal of the present invention.

FIG. 15 is a diagram illustrating a switching operation in one embodiment of the optical waveguide in the photonic crystal of the present invention.

FIG. 16 is a view for explaining a state of waveguide connection in one embodiment of the optical waveguide in the photonic crystal of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st optical medium 2 2nd optical medium 3 3rd optical medium 4 4th optical medium

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G02B 6/12 HF term (reference) 2H047 KA00 LA18 NA01 NA02 NA06 NA08 QA01 QA04 RA08 2H079 AA02 AA03 AA06 AA07 AA08 AA12 BA01 CA05 CA07 DA01 DA05 DA07 EA11 2K002 AB04 BA01 BA06 BA11 BA13 CA01 CA15 DA01 EA13 HA03 HA08 HA09 HA11 HA16 HA28 HA30

Claims (5)

[Claims] 1. A structure in which at least a second optical medium and a third optical medium are periodically arranged in a first optical medium at intervals on the order of the wavelength of incident light. By changing the applied external field condition, the relative relationship between the refractive indexes of the first to third optical media can be changed, and the periodicity of the spatial distribution of the refractive index formed in the structure can be changed. An optical element characterized in that: 2. The structure according to claim 1, wherein, under a first external field condition, a difference between a refractive index of said first optical medium and a refractive index of said second optical medium with respect to said incident light having a predetermined wavelength. Is larger than the difference between the refractive index of the first optical medium and the refractive index of the third optical medium,
The incident light of the predetermined wavelength is modulated by the periodic arrangement of the second optical medium. Under a second external field condition different from the first external field condition, the incident light of the predetermined wavelength is The difference between the refractive index of the first optical medium and the refractive index of the third optical medium is larger than the difference between the refractive index of the first optical medium and the refractive index of the second optical medium. 2. The optical element according to claim 1, wherein the incident light having the predetermined wavelength is modulated by a periodic arrangement of the third optical medium. 3. A first optical medium, a second optical medium periodically arranged in the first optical medium, and a second optical medium formed in the first optical medium. And a third optical medium that is arranged by replacing a continuous part of a periodic structure to be formed. The complex refractive index of the second optical medium and the complex refractive index of the third optical medium are substantially different with respect to light, and the part replaced by the third optical medium is incident at the predetermined wavelength. It functions as a waveguide for light, and in a second external field condition different from the first external field condition, the complex refractive index of the second optical medium and the complex refractive index of the second wavelength The third optical medium has substantially the same complex refractive index as the third optical medium; Optical device in which the portion which is substituted by quality characterized in that it does not function as a waveguide to incident light of said predetermined wavelength. 4. A first optical medium, a second optical medium periodically arranged in the first optical medium, and a second optical medium formed in the first optical medium. A third optical medium arranged by replacing a continuous first portion of the periodic structure to be formed, and a third optical medium to be formed by the second optical medium in the first optical medium A fourth optical medium arranged by replacing the continuous second portion of the first optical medium, and a third continuous optical structure of the periodic structure to be formed by the second optical medium in the first optical medium. And a portion generated in the portion, the periodicity of which is disturbed by the second optical medium, and wherein the first portion and the second portion are each the third portion.
An optical element having a structure connected to a portion of the first optical medium, wherein, under a first external field condition, the complex refractive index of the first optical medium and the second refractive index The complex refractive index of the optical medium and the complex refractive index of the third optical medium are substantially different from each other, and the complex refractive index of the second optical medium and the complex refractive index of the fourth optical medium are substantially different. And the first portion and the third portion function as waveguides for the incident light having the predetermined wavelength. In a second external field condition different from the first external field condition, The complex refractive index of the first optical medium, the complex refractive index of the second optical medium, and the complex refractive index of the fourth optical medium are substantially different from each other with respect to the incident light having the predetermined wavelength, The complex refractive index of the second optical medium is substantially equal to the complex refractive index of the third optical medium. In addition, the second portion and the third portion function as waveguides for the incident light having the predetermined wavelength, so that the branch destination of the incident light having the predetermined wavelength incident on the third portion is determined. An optical element characterized in that it can be switched to one of the first part and the second part. 5. A first optical medium, a second optical medium periodically arranged in the first optical medium, and a second optical medium formed in the first optical medium. A third optical medium arranged by replacing a continuous first portion of the periodic structure to be formed, and a third optical medium to be formed by the second optical medium in the first optical medium A fourth optical medium arranged by replacing the continuous second portion of the first optical medium, and a third continuous optical structure of the periodic structure to be formed by the second optical medium in the first optical medium. And a portion generated in the portion, the periodicity of which is disturbed by the second optical medium, and wherein the first portion and the second portion are each the third portion.
A splitter having a structure connected to a portion of the first optical medium, wherein, for incident light of a first wavelength, the complex refractive index of the first optical medium and the complex refractive index of the second optical medium A refractive index and a complex refractive index of the third optical medium are substantially different from each other;
The complex refractive index of the second optical medium is substantially equal to the complex refractive index of the fourth optical medium, and the first portion and the third portion are incident on the incident light of the first wavelength. For the incident light of a second wavelength different from the first wavelength, the complex refractive index of the first optical medium and the complex refractive index of the second optical medium The complex refractive index of the fourth optical medium is substantially different from the complex refractive index of the second optical medium, and the complex refractive index of the third optical medium is substantially equal to the complex refractive index of the third optical medium. The portion and the third portion function as waveguides for the incident light of the second wavelength, so that the incident light of the first wavelength and the second wavelength incident on the third portion Proceeds to one of the first portion and the second portion, respectively, according to the wavelength. Splitter.