JPH1123875A - Optical integrated element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the optical integrated element which can select the mode of transmitted light and also select the wavelength of the transmitted light. SOLUTION: The optical integrated element has a waveguide layer 24 formed of a material developing refractive index anisotropy or a material having the said material dispersed in matrix. Part of the waveguide layer 24 constitutes a mode filter A which selectively transmits light of TE mode or TM mode. The rest of the waveguide layer 24 constitutes a grating B in grating-shaped refractive index modulation structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical integrated device.

[0002]

2. Description of the Related Art Conventionally, a technique called photobleach using light irradiation has been proposed as one of the techniques for manufacturing a channel-type waveguide (Electronics).
Lett. , 26, 1990, p379). This technique irradiates light to a portion constituting a waveguide layer laminated on a substrate, lowers the refractive index of the irradiated portion, thereby forming a waveguide layer having a core that confines and transmits light. Technology.

[0003] This technique is directed to a waveguide layer formed of an optically isotropic medium, and an analysis on an optically anisotropic medium has not been performed. FIG. 4 of JP-A-62-29913 shows a waveguide type element functioning as a mode filter, in which a metal is disposed on a core of a glass waveguide layer that transmits light, On the other hand, there is disclosed a technique of disposing an optically anisotropic crystal (calcite, Nb ₂ O ₅ film, or the like) having a different refractive index on a core.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a further technical advance from the above-mentioned publication technology, and its object is to provide a waveguide layer formed using a material exhibiting refractive index anisotropy. It is an object of the present invention to provide an optical integrated device capable of selecting a mode of transmitted light and selecting a wavelength of transmitted light.

[0005]

According to the present invention, there is provided an optical integrated device, comprising: a waveguide layer formed of a material exhibiting refractive index anisotropy or a material in which the material is dispersed in a matrix; A part of the waveguide layer constitutes a mode filter that selectively transmits any one of the TE mode and the TM mode light, and the other part of the waveguide layer includes: A grating having a refractive index modulation structure is constituted.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described. -A material exhibiting refractive index anisotropy As a material exhibiting refractive index anisotropy, a light anisotropic refractive index variable material can be employed. As an anisotropic variable refractive index material, it exhibits an anisotropic refractive index before light irradiation, and further, the refractive index changes with light irradiation, and the refractive index change with light irradiation increases and decreases. Refers to a material having components. As such a material, a material that changes its molecular structure by light irradiation can be adopted. As a compound that causes a change in the molecular structure due to light irradiation, specifically, a compound having a carbon-carbon double bond or an azo group capable of being trans-cis photoisomerizable is exemplified.

In order to cause a desired refractive index change, it is important to use a molecule having a large anisotropic refractive index change.
Azobenzene derivatives and stilbene derivatives are preferred. Alkyl groups, carboxyl groups, nitro groups,
By bonding a functional group such as a cyano group, an amino group, or a methoxy group, the anisotropic change can be further increased. Further, electron-withdrawing groups such as nitro group and cyano group,
By introducing electron donating groups such as an amino group and a methoxy group at both ends of the molecule, it is possible to further increase the change in the refractive index anisotropy.

In the above-mentioned materials, reduction, oxidation, cleavage and the like of a carbon-carbon double bond or an azo group may be caused by continuing light irradiation, but any material which causes a desired change in anisotropy can be obtained. It doesn't matter. Rather, it is preferable to the case where the cis-trans isomerization occurs thermally and the refractive index returns to the original value. Light irradiation is performed at a wavelength that causes photoisomerization. Generally, light having a wavelength in the ultraviolet to visible range is applied. A high-pressure mercury lamp is generally used as a light source for light irradiation, but an excimer laser or the like can also be used.

The desired optical anisotropy can be obtained by dispersing or bonding the above-described compound capable of refractive index anisotropy in a polymer, or by dispersing or bonding to an appropriate matrix (for example, resin or glass). Variable refractive index material can be provided. The resin serving as the matrix is not particularly limited. For example, a thermoplastic resin such as a urethane resin, a polyester resin, and an acrylic resin, and a thermosetting resin such as a phenol resin can be used.

In order to exhibit an anisotropic refractive index before light irradiation, a polymer material containing the above-mentioned material is molecularly oriented in the plane of the waveguide layer by spin coating or melt extrusion. Can be realized by: The degree of anisotropy can be controlled by the viscosity, the number of rotations in the spin coating method, the stretching ratio during molding, and the like. In addition, it is preferable that the material and the matrix having the above-described properties have low waveguide loss. Generally, the wavelength range of light used in an optical integrated device is a range from visible light to near-infrared light, and therefore, it is preferable that the loss in the wavelength range where the optical integrated device is used is low.
That is, if the optical integrated device is used in the visible wavelength region, the loss may be low in that region, and if the optical integrated device is used in the near-infrared wavelength region, the loss may be low. As long as the desired low waveguide loss is obtained, the above-mentioned photoisomerizable compound is dispersed or bonded in a polymer, or is dispersed or bonded in an appropriate matrix such as resin or glass, and is anisotropic. The variable refractive index material may be used as it is. Further, it may be used by mixing with another matrix.

Mode Filter In the optical integrated device according to the present invention, a part of the waveguide layer constitutes a mode filter for selectively transmitting either one of the TE mode light and the TM mode light. The mode filter can be composed of a core for confining and transmitting light and a clad coated on the core. Here, when the ordinary light refractive index is defined as no and the extraordinary light refractive index is defined as ne,
In the mode filter according to the present invention, one of the following relationships is set.

Core no> cladding no, and core ne ≦ cladding ne core ne> cladding ne, and core no ≦ cladding no With reference to FIG. FIG. 1 shows a mode filter satisfying the above-mentioned relationship. For example, n of core 2A
o = 1.706, no = 1.702 of the cladding 3A, ne = 1.676 of the core 2A, and ne = 1.680 of the cladding 3A.

According to the relationship described above, the no of the core 2A
> The TE mode light can be confined and transmitted through the core 2A due to the relationship of clad no, and ne of the core 2A ≦ ne of the clad.
, The light in TM mode cannot be confined,
Will radiate. As a result, the mode filter shown in FIG. 1 can function as a TE mode filter capable of selectively extracting only light in the TE mode.

In manufacturing the mode filter shown in FIG. 1, the following can be performed. That is, as shown in FIG. 2, the waveguide layer 24 is laminated on the substrate 20 via the under clad 22, the mask 40 is covered on the portion corresponding to the core 2A, and the portion corresponding to the clad 3A is exposed. In that state, ultraviolet rays are irradiated through the mask 40. In the portion corresponding to the clad 3A thus irradiated, n
As o decreases, ne increases. As a result, a TE mode filter having the above relationship is formed.

Conversely, the mode filter shown in FIG. 3 satisfies the above relationship. For example, no = 1.702 for the core 2A, no = 1.706 for the clad 3A, and ne = 1.680 for the core 2A.
The ne of the clad 3A is set to 1.676. According to the relationship described above, light in the TE mode is emitted and TM
The mode light can be confined in the core 2A and transmitted. Therefore, the mode filter shown in FIG. 3 can function as a TM mode filter that can selectively extract only the TM mode light.

Manufacturing of the mode filter shown in FIG. 3 can be performed as follows. That is, as shown in FIG. 4, the waveguide layer 24 is laminated on the substrate 20 via the under clad 22, and a portion corresponding to the clad 3 </ b> A is covered with the mask 40.
In addition, a portion corresponding to the core 2A is exposed. In that state, ultraviolet rays are irradiated through the mask 40. As a result, in the portion corresponding to the core 2A irradiated, no decreases and ne increases. Thus, a TM mode filter having the above relationship is formed.

Grating In the optical integrated device of the present invention, as described above, the other part of the waveguide layer constitutes a grating. Generally, a grating is formed with a waveguide structure in series with a mode filter. The grating can be constituted by a refractive index modulation structure in which the refractive index periodically changes in the core.
The portion where the refractive index changes periodically can be formed by causing an irradiation light beam to interfere and generate interference fringes. In some cases, the waveguide layer may be formed in a so-called relief type in which periodic irregularities are arranged on the surface of the core through which light is transmitted.

FIG. 5 shows an essential part of an example of the embodiment. In this example, an under clad 22 is laminated on a substrate 20 as a base,
The waveguide layer 24 is laminated thereon. One side of the waveguide layer 24 forms the mode filter A, and the other side of the waveguide layer 24 forms the grating B. The mode filter A and the grating B have a serial waveguide structure. In the mode filter A, the waveguide layer 24 includes a core 2A for confining and transmitting either the TE mode light or the TM mode light, and the cladding 3 disposed on both sides of the core 2A.
A. The relationship between the refractive indices of the core 2A and the cladding 3A is set to one of the above or one of the above.

In the grating B, the waveguide layer 24
Like the core 2A of the mode filter A, includes a core 2B for confining and transmitting one of the TE mode light and the TM mode light, and claddings 3B arranged on both sides of the core 2B. In the core 2B of the grating B, a lattice-shaped refractive index modulation structure is formed along the length direction. In FIG. 5B, the period of the refractive index modulation structure is indicated by Λ.

In the optical integrated device of the embodiment shown in FIG. 5, the mode filter A may be set to the incident side and the grating B may be set to the output side. Conversely, the grating B may be on the incident side and the mode filter A may be on the outgoing side. In the embodiment shown in FIG. 5, the mode filter A and the grating B are provided one by one in a serial waveguide structure, but the number of the mode filters A and the It is also possible to increase the number.

Mode filter A in the optical integrated device
2A of the grating B and the core 2B of the grating B may be of a channel type in which they are embedded as shown in FIGS. Alternatively, the core 2A, 2B may be a ridge type projecting outward. In some cases, like a fiber, a cylindrical core and a clad may be used.

Above the waveguide layer 24, there may be an over-cladding. In this case, the material of the over-cladding may be the same as the refractive index of the claddings 3A and 3B in the horizontal direction, or may be a material having another refractive index as long as the performance of the mode filter is not impaired. Manufacturing Method In manufacturing the above-described optical integrated device, a light irradiation process for forming the mode filter A and a light irradiation process for forming the grating B can be adopted.

(1) Light Irradiation Processing Mode filter A
The light irradiation for forming is performed at a wavelength that causes photoisomerization. In general, light having a wavelength from the ultraviolet region to the visible region is irradiated, and it does not matter whether laser light or non-laser light is used. As a light source for light irradiation when forming the mode filter A, a high-pressure mercury lamp is generally used, but an excimer laser or the like can also be used.

In the light irradiation, the irradiation light intensity and irradiation time necessary to cause a desired amount of change in the refractive index in the refractive index anisotropic variable material are appropriately selected. When the temperature of the variable refractive index anisotropic material is increased to shorten the irradiation time, generally, the efficiency of the change in the refractive index of the variable refractive index anisotropic material tends to increase. The relationship between the light irradiation time and the change in the refractive index is shown in FIG. As can be understood from the test results in FIG. 8, in the above-described variable refractive index anisotropy material, the normal light refractive index no is reduced by light irradiation as illustrated by Δ and ▲, and is illustrated by Δ and ●. Then, the extraordinary light refractive index ne increases.

In manufacturing the grating B, in the core of the waveguide layer through which light is transmitted, interference fringes of the irradiated light are generated by a two-beam interference method, a phase grating method, or the like. A method of forming a rate modulation structure can be adopted. The light for producing the grating B is performed in a wavelength range that causes photoisomerization as described above,
Generally, light having a wavelength in the ultraviolet to visible range can be employed. Particularly, laser light having coherence is preferable.

FIG. 6 shows an embodiment in which a grating-like refractive index modulation structure of the grating B is formed using the two-beam interference method.
In this case, the laser beam having a wavelength in the ultraviolet range is split into two light beams by the beam splitter 100, and the split light beam is reflected by the mirror 102, and the incident angle θ1 with respect to the core 2B of the grating B, The interference fringes 106 are generated on the core 2B of the grating B while making θ2 equal.
As a result, as shown in FIGS. 5A and 5B, in the core 2B of the grating B, a lattice-shaped refractive index modulation portion is formed at a predetermined period Λ. In the two-beam interference method, by adjusting the position of the mirror 102, the grating B
Can be controlled.

FIG. 7 shows an embodiment in which the refractive index modulation structure of the grating B is formed by using the phase grating method. In this case, a laser beam having a wavelength in the ultraviolet region is used, and interference fringes 206 are generated on the core 2B of the grating B using the diffracted light by the phase grating 200. Thereby, in the core 2B, a lattice-shaped refractive index modulation portion is formed at a predetermined period. In the phase grating method, the period Λ of the grating B can be controlled by the pitch of the grating of the phase grating 200.

The period に お け る in the grating B is generally set to a constant interval, but may be changed continuously in some cases. In this case, it is advantageous to realize functions such as wavelength dispersion correction. If the period Λ of the refractive index modulation portion of the core 2B of the grating B is appropriately selected, light having a wavelength corresponding to the period で き can be transmitted through the core 2B, and light of other wavelengths is not transmitted but reflected. That is, in FIG. 5, even if the lights of the wavelengths λ _1, λ _{2, and} λ ₃ are respectively incident on the optical integrated device, the light of the wavelength corresponding to the period Λ is reflected and not transmitted, and the light of other wavelengths is not transmitted. To Penetrate. Therefore, the period に お け る in the grating B defines the wavelength of light transmitted through the core 2B of the grating B and the wavelength of light reflected by the core 2B. Therefore, a waveguide structure having a reflection type wavelength selection function is provided.

Here, when the period of the refractive index modulation structure of the grating B is Λ, the wavelength of the light reflected by the grating B is λ _0, and the transmission refractive index of the core 2 B of the grating B is n _core , Specifically, it is considered that the following equation (1) holds. λ ₀ = 2 · n _core · Λ (1)

[0030]

Embodiments of the present invention will be described below. First, a method of synthesizing the variable refractive index anisotropy material constituting the waveguide layer used in the examples will be described, and then a method of manufacturing the optical integrated device will be described for each item. In this example, the molecular structure was confirmed by an infrared absorption spectrum and an H nuclear magnetic resonance spectrum. The measurement of the melting point and the glass transition temperature was performed by a differential scanning calorimeter. The refractive index was determined from the mode angle when light was incident on the waveguide layer using a coupling prism to excite the waveguide mode.

(Method of synthesizing variable refractive index anisotropy material)
7.61 g of methyl-4-nitroaniline was added to 100 ml of water.
And a 36% aqueous hydrochloric acid solution (45 ml), and cooled to 3 ° C. 3.80 g of sodium nitrite dissolved in 18 ml of water was added to the solution. Keep the solution at 3 ° C for 1
Stirred for hours. Further, a solution obtained by dissolving 9.76 g of m-tolyldiethanolamine in a mixed solution of 125 ml of water and 7.5 ml of a 36% hydrochloric acid aqueous solution was added to this solution over 30 minutes, followed by stirring at 3 ° C. for 20 minutes, and further at 20 ° C. At 6
The reaction was stirred for 0 minutes. A solution obtained by dissolving 35.4 g of potassium hydroxide in 200 ml of water was added to the reaction mixture for neutralization, and the precipitated crude product was separated by filtration, washed with water, and dried.
The product was recrystallized twice from ethanol to give 4-N, N-bis (2-
(Hydroxyethyl) amino-2,2′-dimethyl-4 ′
-Nitroazobenzene was obtained (yield; 80%, melting point; 1).
69 ° C).

[0032]

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0.686 g of the compound of the structural formula (Chemical Formula 1) and 0.500 g of tolylene-2,4-diisocyanate are mixed with N
-Methyl-2-pyrrolidone dissolved in 10 ml
Stirred at C for 1 hour. After cooling this solution to 20 ° C,
0.109 g of trans-2,5-dimethylpiperazine was added and reacted by stirring at 20 ° C. for 7 hours. The reaction mixture was poured into 400 ml of a 1: 1 mixture of ethanol and hexane, and the precipitated polymer precipitated was separated by filtration and dried under reduced pressure.

The resulting polymer was confirmed to have the following structural formula (Formula 2) (yield: 89%, glass transition temperature: 142 ° C., intrinsic viscosity in N-methyl-2-pyrrolidone: 0.1). 28 dl / g, absorption maximum wavelength; 474n
m).

[0035]

Embedded image

Next, 1.50 g of the compound of the structural formula (Chemical Formula 1) synthesized as described above and 1.571 g of 4,4′-diphenylmethane diisocyanate were dissolved in 90 ml of N-methyl-2-pyrrolidone. And stirred at 100 ° C. for 90 minutes. After cooling the solution to 20 ° C., N-methyl-2 was added.
Trans-2,5- dissolved in 10 ml of pyrrolidone
0.239 g of dimethylpiperazine was added and reacted by stirring at 20 ° C. for 5 hours. The reaction mixture is ethanol 300
The solution was poured into 0 ml, and the precipitated precipitated polymer was separated by filtration and dried under reduced pressure.

The resulting polymer was confirmed to have the following structural formula (formula 3) (yield: 96%, glass transition temperature: 114 ° C., intrinsic viscosity in N-methyl-2-pyrrolidone: 0.1). 80 dl / g, absorption maximum wavelength; 475 n
m).

[0038]

Embedded image

(Manufacturing Method of Optical Integrated Device) The manufacturing method of this embodiment is an example of forming an optical integrated device in which the mode filter A and the grating B shown in FIG. 5 are arranged in a serial waveguide structure. As a substrate functioning as a substrate, a crystal axis <1
00>, a single-sided mirror-finished 4-inch silicon wafer (manufactured by Mitsubishi Materials; n-type) having a thickness of about 500 μm
The divided one was used.

HF: pure water = 1: 50
For about 1 minute to wash the surface. Next, the resultant was washed with running pure water for about 5 minutes and then dried with a spin drier.
Next, polyimide (PlX2400 manufactured by Hitachi Chemical Co., Ltd.) was used as a material for forming the under clad 22, polyimide was applied to the substrate, and heat treatment was performed (at 150 ° C. for 1 hour, 3 hours).
This was performed at 00 ° C. for 1.5 hours to obtain an under clad 22.

The thickness of a thin film formed on glass under the same conditions is measured by a stylus type surface roughness needle (SloanTechnology).
y Corp .; DEKTAKII) and used as the sample thickness. The film thickness was similarly determined in the following steps. The thickness of the polyimide layer which is the under cladding 22 is about 7 μm.
Met. In forming a polymer thin film portion corresponding to the waveguide layer 24, the refractive index anisotropy variable material manufactured as described above is mixed with pyridine as a solvent to obtain a relatively low concentration (1% by weight) of pyridine. A solution formed. The pyridine solution was filtered through a 0.2 μm Teflon filter (Advantech Toyo; DISMIC13P), and then concentrated by an evaporator to obtain a high-concentration solution (about 6% by weight). Thereafter, the high-concentration solution was applied on the under clad 22 by spin coating using a photoresist spinner, and the waveguide layer 24 was laminated.

After the above spin coating, at room temperature, about 6
Vacuum drying was performed for hours. The thickness of the obtained waveguide layer 24 was 1.3 μm. Next, light irradiation treatment called photobleaching was performed. That is, a light source unit for an exposure apparatus (manufactured by USHIO Inc .; Multilight ML-251A / B) capable of irradiating parallel light using an ultra-high pressure mercury lamp (USH-250BY manufactured by USHIO Inc.) as a light source, The layer 24 was irradiated with ultraviolet light (UV). The irradiation power was 80 mW / cm ² . At the time of light irradiation, a photomask (manufactured by Toppan Printing) drawn on quartz glass with low-reflection chrome was used. The photomask was brought into contact with the sample surface, the sample was heated to 110 ° C., and the sample was irradiated from above the sample through the mask for 1 hour (see FIG. 2).

The core 2A and the clad 3A constituting the mode filter A were formed by the above-described ultraviolet irradiation. In the present embodiment, the relationship between the refractive indices no and ne in the core 2A and the clad 3A is one of the relationships described above. In this embodiment, when forming the mode filter A, the core 2B of the grating B as well as the core 2A of the mode filter A is irradiated with ultraviolet rays from the above-described ultrahigh-pressure mercury lamp.

Thereafter, the core 2B of the grating B is formed by a two-beam interference method using a third harmonic beam (wavelength: 355 nm) oscillated from a pulsed Nd: YAG laser.
Only the grating-like refractive index modulation structure was written. The mirror angle at the time of writing was adjusted so that the period (pitch) グ of the grating B was 243 nm. In this case, the irradiation treatment was performed at a sample temperature of 80 ° C. for 2 hours.

Based on the above equation (1) showing λ ₀ = 2 · n _core · Λ, if n _{core of} the core 2B is 1.7, 830 nm ≒ 2 × 1.7 × 243 nm. Therefore, theoretically, the light of 830 nm is reflected and does not transmit even if it enters the grating B. (Light transmission experiment) A light transmission experiment was performed using the sample manufactured as described above. The mode filter A of this sample is of the type shown in FIGS. 1 and 2, and does not transmit the TM mode but transmits the TE mode. In this experiment, the wavelength 830
A semiconductor laser having a wavelength of 1.3 nm and a semiconductor laser having a wavelength of 1.3 μm were used as incident light sources. In the light transmission experiment, basically, a semiconductor laser, a lens, a Ramipole fiber polarizer (manufactured by Sumitomo Osaka Cement) as an optical fiber, and an optical integrated device as a sample were arranged in this order. The mode filter A of the optical integrated device is coupled to the Ramipole fiber polarizer with the incident portion as the incident portion, and the grating B of the optical integrated device is
Was arranged at the emission part.

When light having a wavelength of 830 nm was used to excite the TE mode and the TM mode at an intensity of 1: 1 and made incident on the sample, no guided light could be observed.
That is, the light having a wavelength of 830 nm was reflected by the grating B and was not transmitted. In addition, using light having a wavelength of 1.3 μm,
When the TE mode and the TM mode were excited at an intensity of 1: 1 and made incident on the sample, the guided light could be observed. That is, light having a wavelength of 1.3 μm (TE mode) transmitted through the grating B. Therefore, it was observed that the grating B of the optical integrated device according to the present example functions as a wavelength selection filter.

(Irradiation Test) In the case where the refractive index anisotropy variable material according to the above-described embodiment was employed, the relationship between the irradiation time of light irradiation treatment and the degree of change in the refractive index was examined. Further, the relationship between the temperature of the sample and the degree of change in the refractive index during the irradiation treatment was examined. In the measurement of the refractive index, a prism coupler (manufactured by Metricon; PC2010) was used, and a wavelength of 633 nm and a wavelength of 830 nm were used as guided light.

The test results are shown in FIGS. FIG. 8 shows the relationship between the irradiation time and the refractive index (when the irradiation temperature is 110 ° C.). FIG. 9 shows the relationship between the irradiation temperature and the refractive index (when the irradiation time is one hour). 8 and 9, ■ indicates no when light with a wavelength of 633 nm is used, and ● indicates ne when light with a wavelength of 633 nm is used. ▲ indicates no when light with a wavelength of 830 nm is used, and Δ indicates ne when light with a wavelength of 830 nm is used.

As can be understood from the test results shown by Δ and ▲ in FIG. 8, the refractive index of n _O has been reduced by the light irradiation treatment, and can be understood from the test results shown by Δ and ● in FIG. Thus, it was confirmed that the refractive index of ne increased. Further, as can be understood from FIG. 9, it was confirmed that in the refractive index anisotropic variable material according to the above example, the refractive index was affected by the temperature of the sample. In particular, the higher the temperature,
It was confirmed that the rate of change in the refractive index was large.

(Supplementary Note) The following technical idea can be understood from the above description. Using a waveguide layer formed of a material having a variable refractive index anisotropy by light irradiation or a material obtained by dispersing the aforementioned material in a matrix, and irradiating the waveguide layer with light, the TE mode or the TM mode is used. Forming a mode filter in the waveguide layer to selectively transmit one of the lights, and irradiating the waveguide structure of the waveguide layer with light to form a grating having a refractive index modulation structure in the waveguide layer. And a method for manufacturing an optical integrated device.

[0051]

According to the present invention, a part of the waveguide layer is made of TE.
A mode filter that selectively transmits one of the light in the mode and the TM mode is formed, and the other part of the waveguide layer forms a grating that selects the wavelength of light. An integrated element in which the layers are formed of the same material can be obtained. Therefore, an integrated element having a simple configuration and a simple manufacturing process can be obtained.

Further, according to the present invention, since the waveguide structure in the mode filter and the waveguide structure in the grating are continuously connected by the same material, the coupling loss at the connection between the mode filter and the grating is reduced. be able to. The ordinary refractive index is no,
When the extraordinary light refractive index is defined as ne, the mode filter according to the present invention can set one of the following relationships by adjusting ne and no in the waveguide layer using light irradiation. .

Core no> cladding no and core ne ≦ cladding ne core ne> cladding ne and core no ≦ cladding no In this way, either TE mode or TE mode A mode filter that can select and transmit only the light of

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a concept of a mode filter portion of a waveguide layer.

FIG. 2 is a configuration diagram conceptually showing a manufacturing process when a mode filter having the form shown in FIG. 1 is formed.

FIG. 3 is a configuration diagram illustrating a concept of a mode filter of a waveguide layer according to another embodiment.

FIG. 4 is a configuration diagram conceptually showing a manufacturing process when a mode filter having the form shown in FIG. 3 is formed.

FIG. 5 is a perspective view showing the general concept of an optical integrated device having a mode filter and a grating.

FIG. 6 is a configuration diagram conceptually showing a form in which a grating is formed by employing the two-beam interference method.

FIG. 7 is a configuration diagram conceptually showing a form in which a grating is formed by employing a phase grating method.

FIG. 8 is a graph showing a relationship between irradiation time and refractive index in light irradiation.

FIG. 9 is a graph showing the relationship between sample temperature and refractive index during light irradiation.

[Explanation of symbols]

In the figure, A is a mode filter, B is a grating, 20
Is a substrate (base), 24 is a waveguide layer, 2A and 2B are cores, 3
A and 3B show claddings.

Claims (1)

[Claims] A waveguide layer formed of a material exhibiting refractive index anisotropy or a material obtained by dispersing the material in a matrix; and a base holding the waveguide layer. A part of the waveguide layer constitutes a mode filter for selectively transmitting either one of the TE mode light and the TM mode light, and another part of the waveguide layer constitutes a grating having a refractive index modulation structure. An optical integrated device, comprising: