JPH07270732A - Optical waveguide type wavelength selector - Google Patents

Abstract

PURPOSE:To provide an optical waveguide type wavelength selector which is capable of surely executing wavelength selection by a simple constitution, in wide in central wavelength varying range of its wavelength selection in the case of varying the central wavelength, lessens optical damage and has excellent light power durability. CONSTITUTION:This optical waveguide type wavelength selector has an optical waveguide 3 having first and second end faces 21 and 22 and consisting of a first optical waveguide part 1 and a second optical waveguide part 2 and a periodic refractive index disturbing structural part 4 where this optical waveguide 3 periodically forms refractive index disturbance in the propagating direction of this optical waveguide 3. The first optical waveguide part 1 has a refractive index higher than the refractive index of the second optical waveguide part 2 and at least a part thereof is disposed in contact with the surface of the second optical waveguide part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength selection device having a wavelength dependence of light.

[0002]

2. Description of the Related Art In recent years, in the fields of optical communication and optical measurement, an optical waveguide type wavelength selecting device is one of the important elements in the construction of an optical integrated circuit in a functional element for optical control.

As this optical waveguide type wavelength selecting device, for example, there is an optical waveguide type wavelength selecting device in which a grating is formed by using LiNbO ₃ (LN) as a substrate for easily producing an optical waveguide having a large electro-optic coefficient. .

[0004]

As described above, there is an optical waveguide type wavelength selecting element using a diffraction type grating having a narrow wavelength selecting band. For example, a central wavelength is obtained by a refractive index modulation due to an electro-optic effect or the like. When changing, the variable range is small.

Further, in an optical waveguide type functional device using LN as a substrate, a Ti diffusion waveguide is most used as a waveguide because it has good propagation characteristics and is easy to manufacture, but the problem that optical damage is remarkable There is.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to reliably perform wavelength selection with a simple configuration, and when the center wavelength is variable, the wavelength selection center wavelength tunable range is (EN) Provided is an optical waveguide type wavelength selection device which has a wide area, small optical damage, and excellent durability of optical power.

[0007]

The first aspect of the present invention has first and second end faces 21 and 22 as shown in FIG. 1 which is a schematic sectional view of the basic structure thereof. An optical waveguide 3 including a wave portion 1 and a second optical waveguide portion 2; and a periodic refractive index disturbing structure portion 4 in which the optical waveguide 3 periodically causes refractive index disturbance in the propagation direction of the optical waveguide 3. It is configured to have.

The first optical waveguide portion 1 has a refractive index larger than that of the second optical waveguide portion 2, and at least a part of the first optical waveguide portion 1 is provided in contact with the second optical waveguide portion 2. It has a different configuration.

In the second aspect of the present invention, the periodic refractive index disturbing structure portion 4 has a structure in which the refractive index periodically changes at the interface between the first optical waveguide portion 1 and the second optical waveguide portion 2. Is.

In the third aspect of the present invention, the periodic refractive index disturbing structure 4 has a structure in which the refractive index periodically changes on the surface of the first optical waveguide 1.

According to a fourth aspect of the present invention, an optical waveguide 3 composed of a first optical waveguide section 1 and a second optical waveguide section 2 is arranged on a substrate 11, and a second optical waveguide section 2 is located on the substrate 11 side. To be formed. The second optical waveguide section 2 has a refractive index higher than that of the substrate 11, and the first optical waveguide section 1 has a refractive index higher than that of the substrate 11 and the second optical waveguide section 2. It has a refractive index and is configured. Then, the periodic refractive index disturbing structure portion 4 is configured to have a periodic refractive index change at the interface between the second optical waveguide portion 2 and the substrate 11.

In a fifth aspect of the present invention, the periodic refractive index disturbing structure 4 is constituted by a periodic refractive index change caused by an electric field from an electrode.

In a sixth aspect of the present invention, the first and second optical waveguide sections 1 and 2 have a proton exchange waveguide configuration.

According to a seventh aspect of the present invention, the first optical waveguide section 1 has a dielectric film structure and the second optical waveguide section 2 has a proton exchange waveguide structure.

In the eighth aspect of the present invention, the first and second optical waveguide portions 1 and 2 have a dielectric film structure.

In the ninth aspect of the present invention, the optical waveguide in the first end face 21 is only the first optical waveguide portion 1, and the second end face 2
2, the optical waveguide is the second optical waveguide section 2 only.

In the tenth aspect of the present invention, the optical waveguide is the first optical waveguide portion 1 at the first and second end faces 21 and 22.
The configuration is only.

The eleventh aspect of the present invention is configured such that the optical waveguide is only the second optical waveguide portion 2 on the first and second end faces 21 and 22.

In the twelfth aspect of the present invention, the substrate 11 is LiTa _x.
Nb _1-X O ₃ (0 ≦ x ≦ 1).

[0020]

As described above, in the configuration of the present invention, the first and second optical waveguide portions 1 and 2 having different refractive indexes are used.
The multi-mode optical waveguide 3 for 0th-order and 1st-order mode propagation is constituted by the waveguide portions of the layers, and the periodic refractive index disturbing structure portion 4 is formed.
By using the wavelength dependence of the mode conversion by the above, wavelength selection, for example, a wavelength band pass filter or a wavelength band cut filter can be configured.

The operation (operation) of the device of the present invention will be described.
Now, for example, as shown in FIG. 1, the substrate 11 having a refractive index n _S
Above, by the first and the B portion by two layer waveguide of the optical waveguide portion 1 and the refractive index n ₂ becomes the second optical waveguide portion 2, a first waveguide of only the light waveguide 1 consisting refractive index n ₁ Consider an element which is composed of the section A and the section C formed by the waveguide of only the second optical waveguide section 2 and has the following relationship (Equation 1).

[0022]

[Equation 1] n ₁ > n ₂ > n _S ··· (1)

Further, Δn ₁ = n ₁ −n _S , Δn ₂ = n ₂
-N _S.

At this time, the two-layer waveguide of the B section is a multi-mode waveguide in which the 0th-order mode and the first-order mode are guided modes in the depth direction, and the single-layer waveguides of the A section and the C section are Use a single-mode waveguide.

[0025] First, explaining part B, each of the mode field of the zero-order and first-order modes are as shown curve b ₀ and the curve b ₁ in FIG.

The mode field of the first-order mode has an asymmetric distribution in the depth direction because it is a two-layer waveguide having different refractive indexes. The larger the Δn ₁ is than the Δn ₂ , the more remarkable the asymmetry.

Then, with respect to the traveling direction of light in this waveguide, a periodic refractive index disturbing structure portion 4 in which a periodic disturbance is formed in the refractive index distribution, for example, a first optical waveguide portion as shown in FIG. The depth of 1 is periodically changed with the period Λ to form a grating whose refractive index is changed periodically.

At this time, due to the refractive index modulation grating at the interface between the first optical waveguide section 1 and the second optical waveguide section 2, the 0th-order mode and the 1st-order mode have a wavelength λ ₀ based on the period Λ.
Then, coupling is performed through phase matching, and a large power conversion occurs between the 0th-order mode and the 1st-order mode.

The phase-matching λ ₀ is given by the following (Equation 2) when the effective refractive indices of the 0th-order mode and the 1st-order mode are N ₀ and N ₁ , respectively.

[0030]

(2) λ ₀ = (N ₀ −N ₁ ) Λ (2)

The power conversion efficiency between the modes depends on the depth of the grating and the degree of electric field overlap in the grating portion of the 0th-order mode and the 1st-order mode.

Therefore, when light is made incident from the end face 21 of the A section waveguide, in the AB section coupling, the 0th order mode of the B section is coupled due to the mode field distribution shown by the curve a.

Here, in the B part, the excited 0th-order mode is converted into the 1st-order mode in propagating at the wavelength λ ₀ based on the above (Formula 2) by the grating of the B part, and other wavelengths. Does not convert and propagates as it is in the 0th mode.

Here, the depth of the grating, that is, the periodic refractive index disturbing structure portion 4 is such that the maximum conversion efficiency is obtained at the wavelength λ ₀ when propagating from the AB coupling portion to the BC coupling portion. Set to. That is, the depth is selected so that the complete bond length is obtained.

In the B-C coupling section, the coupling to the C section is due to the mode field distribution shown by the curve c in FIG. Is almost cut. Further, in order to improve the coupling with the first-order mode, it is necessary to increase the asymmetry of the mode field distribution of the first-order mode.
It is necessary that n ₁ be larger than Δn ₂ .

In this way, for the light incident from the end face of the A part, only the light of the wavelength λ ₀ is output from the end face 22 of the C part, that is, wavelength selection can be performed.

Further, according to the configuration of the present invention, when the central wavelength of the wavelength selection band is made variable, an optical waveguide type wavelength selection device having a wide variable range can be manufactured.

Further, for example, LN or LiTaO ₃ (LT)
When a substrate such as is used as the substrate, the optical waveguide can be a proton exchange waveguide or a thin film waveguide, so that the optical waveguide type wavelength selection device with less optical damage and excellent optical power durability in the optical waveguide type wavelength selection device. Can be configured.

[0039]

EXAMPLE An example of the present invention will be described with reference to FIG. 2 showing a schematic perspective view of the example. The present invention has the first and second end faces 21 and 22, and includes the first optical waveguide section 1
And a second optical waveguide portion 2 and an optical waveguide 3 and a periodic refractive index disturbance structure portion 4 in which the optical waveguide 3 periodically forms a refractive index disturbance in the propagation direction of the optical waveguide 3. And

The first optical waveguide section 1 has a refractive index higher than that of the second optical waveguide section 2, and at least a part of the first optical waveguide section 1 is provided in contact with the second optical waveguide section 2. It has a different configuration.

The substrate 11 is made of LiTa _x Nb _1-x O ₃ (0
≦ x ≦ 1), x = 0, that is, a LN z substrate having a z-axis, for example, in the thickness direction of LN, is used, and the first and second optical waveguide sections 1 and 2 are
A proton exchange waveguide structure can be formed in which the Li ions and the H ions in the LN substrate 11 are exchanged to increase the refractive index to form a waveguide. In this case, the second optical waveguide unit 2 is formed after the proton exchange. The annealed proton-exchanged waveguide that has been subjected to high-temperature annealing has a structure in which its refractive index is made smaller than that of the first optical waveguide portion by high-temperature annealing.
The depth of the first optical waveguide portion 1 is periodically changed, and the grating, that is, the periodic refractive index disturbing structure portion 4 is formed.
Are configured.

An example of a method of forming the first and second optical waveguide portions 1 and 2 by the above-mentioned proton exchange path and the periodic refractive index disturbing structure portion 4 at the interface between them will be described with reference to FIG. To do.

In this case, as shown in FIG. 3A, z of LN
A substrate 11 is prepared, and an opening 41W is formed in a portion of one main surface thereof where the second optical waveguide portion 2 is finally formed.
A mask layer 41 made of a is formed. And the substrate 11
The mask layer 41 by immersing the mask layer in hot phosphoric acid at 200 ° C.
To form the second proton exchange part 32 selectively proton-exchanged through the opening 41W of the
High temperature annealing at 0 ° C. is performed in the atmosphere to form the second optical waveguide section 2.

After this annealing or before the annealing, the mask layer 41 is removed, and in the portion where the periodic refractive index disturbing structure 4 is finally formed on the substrate 11 again, the light propagation direction is finally made with a predetermined pitch and width. Then, a mask layer 42 made of, for example, Ta, in which slit-shaped openings 42W extending in the following direction are arranged in parallel, is formed.

Then, the substrate 11 is again immersed in hot phosphoric acid at 200 ° C., for example, to form parallel-arranged stripe-shaped proton exchange portions 33 in which protons are selectively exchanged through the openings 42W of the mask layer 42.

Thereafter, as shown in FIG. 3C, the mask layer 4
2 is removed, and the surface of the substrate 11 is immersed in hot phosphoric acid at 200 ° C., for example, to form the first proton exchange part 31 on the entire surface.

Thereafter, as shown in FIG. 3D, the end of the first proton exchange section 31 on the second proton exchange section 32 is removed by etching. In this way, on the substrate 11,
The second optical waveguide section 2 formed by the second proton exchange section 32, and the first optical waveguide section 1 formed by the first proton exchange section 31 and the stripe-shaped proton exchange section 33 thereon. And are formed. The first optical waveguide portion 1 formed in this manner has a part of the first optical waveguide portion 1 at the interface with the second optical waveguide portion 2, and the deep stripes entering the second optical waveguide portion 2 are parallel to each other. The periodic refractive index disturbing structures 4 are formed with a predetermined pitch.

As described above, the waveguide formed by the proton exchange has the effect of confining light by changing the refractive index only in the z-axis direction. In the example shown in FIG. 2, stripes of, for example, SiO ₂ are traversed on the periodic refractive index disturbing structure 4 along the direction in which optical waveguide (light propagation) is performed on the substrate 11.
This is a case where the dielectric film 5 made of is loaded to form a loading type three-dimensional waveguide. The stripe-shaped dielectric film 5 can be formed, for example, by sputtering SiO ₂ over the entire surface and then pattern-etching it by photolithography.

In the case of this configuration, the relationship of the above (Equation 1) is established. Then, the optical waveguide 3 having this configuration
Of the first optical waveguide portion 1 is used as a light incident end surface, and the second optical waveguide portion 2 on the opposite side is formed.
The second end face 22 on the side composed of only the light is used as the light emission end face.

In the device of the present invention having this structure, when light is incident from the end face of the first end face 21 having only the first optical waveguide section 1, only the light having the wavelength λ ₀ satisfying the above (Formula 2) As described above, the first and second optical waveguide portions have only the second optical waveguide portion 2 in the laminated portion by performing mode conversion by the phase matching between modes by the periodic refractive index disturbing structure portion 4. The light is emitted from the second end face 22. That is,
A wavelength band pass filter operation is performed.

In the above-described embodiment, the first and second optical waveguides 1 and 2 are both proton exchange waveguides. As shown in the schematic perspective view of FIG.
The optical waveguide 2 and the periodic refractive index disturbing structure 4 of FIG.
Although the proton exchange is performed by the same method as described in B and B to form in the LN substrate 11, the first optical waveguide portion 1 is formed by depositing the first optical waveguide portion 1 on the substrate 11, for example, Ta ₂ O ₅ . Alternatively, the dielectric film 6 may be used.
4, parts corresponding to those in FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

The device of the present invention, as shown in the schematic perspective view of FIG. 5, has first and second dielectric waveguides 1 and 2 formed on a substrate 11 together. It can be constituted by the body membranes 6 and 7.

In this case, the portion where the second optical waveguide portion is formed on one main surface of the substrate 11 is etched to form the recessed portion 8, and the recess 8 is formed in substantially the same plane as the one main surface of the substrate 11. The second dielectric film 7 made of, for example, Ta ₂ O _5.
Is formed, and the surface of the second dielectric film 7 is selectively etched to finally extend to a portion that constitutes the periodic refractive index disturbing structure portion 4 in a direction transverse to the light propagation direction. Striped irregularities are arranged in parallel. Then, the first dielectric film 6 made of, for example, Nb ₂ O ₅ is spread over the second dielectric film 7 of the substrate 11 and the other portions where the concave portions 8 are not formed so as to fill the concave and convex portions 9. Form.

In this structure, since the depth of the first dielectric film 6 forming the first optical waveguide portion 1 is changed in the portion where the concave-convex portion 9 is formed, the refractive index is periodic here. The periodic refractive index perturbation structure portion 4 that changes to Also in this case, in FIG. 5, parts corresponding to those in FIG.

In each of the above examples, the first and second
In the case where the periodic refractive index disturbing structure 4 is formed at the interface between the optical waveguides 1 and 2, the periodic refractive index disturbing structure 4 propagates through the first optical waveguide 1 as described above. Since it suffices to form the field distribution of the 0th-order mode and the field distribution of the 1st-order mode propagating in the second optical waveguide portion 2 at a depth position where they overlap, the formation of this periodic refractive index disturbance structure portion 4 The position is not limited to the interface between the first and second optical waveguides 1 and 2, and the position may be formed, for example, on the upper first optical waveguide 1.

For example, as shown in FIG. 6, a pair of comb-teeth-shaped metal electrodes 10A and 1 made of, for example, aluminum Al is provided on the laminated portion of the first optical waveguide portion 1 and the second optical waveguide portion.
0B is arranged and a predetermined, for example, variable DC voltage E is applied between them.

According to this configuration, the electrodes 10A and 10A
By B, an electric field can be generated in the lateral direction to periodically modulate the refractive index in the mode propagation direction to generate a grating, and by selecting the voltage E, the depth of the grating can be adjusted and selected. The coupling of the first-order mode can be set well. In FIG. 6 as well, parts corresponding to those in FIG.

Further, in the example shown in FIG. 7, the periodic refractive index disturbing structure portion 4 is formed by the unevenness formed on the surface of the first optical waveguide portion 1, and in this case as well, there is a difference between the modes. Phase matching can occur. In FIG. 7 as well, parts corresponding to those in FIG.

Further, the periodic refractive index disturbing structure portion 4 is shown in FIG.
Alternatively, it can be formed on the surface of the second optical waveguide 2 on the substrate 11 side as shown in FIG. In this case, for example, unevenness is formed on the surface of the substrate 11 by etching or the like, and the second
The periodic refractive index disturbing structure portion 4 can be formed by forming the optical waveguide portion 2 and changing the depth thereof. In FIG. 8 as well, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

In any of the configurations shown in FIGS. 4 to 8, the wavelength bandpass filter operation can be performed in the same manner as described with reference to FIGS.

Although the optical waveguide type wavelength selecting device that performs the wavelength band pass filter operation is configured in the configurations described in FIGS. 1, 2 and 4 to 8, the optical waveguide type wavelength selecting device that performs the wavelength band cut filter operation is used. A selection device can also be configured.

In this case, FIG. 9 or FIG.
As shown in FIG. 1, the first optical waveguide portion 1 constituting the optical waveguide 3 is
Alternatively, one of the second optical waveguide portions 2 is formed over the entire length of the optical waveguide, and a part of the second optical waveguide portion 2 and the other second optical waveguide portion 2 or the first optical waveguide portion 1 have a cycle. The refractive index disturbing structure portion 4 is arranged and formed.

According to this configuration, in FIG. 9 or FIG. 10, when the light including the wavelength λ ₀ from the first end face 21 is made incident on the first or second optical waveguide section 1 or 2, the periodic refraction is performed. With respect to the wavelength λ ₀ that is phase-matched with the disturbing structure portion 4, a loss occurs due to coupling to the second or first optical waveguide portion 2 or 1, so that the output light with this wavelength λ ₀ cut is Can be emitted from the end face 22 of the.

9 and 10, the periodic refractive index disturbing structure portion 4 can be formed at the interface between the first and second optical waveguide portions 1 and 2, and the first and second optical waveguide portions 1 and 2 can also be formed.
It can also be formed on the upper surface side of the optical waveguide section 1 or on the second substrate 11 side. As described above, the periodic refractive index disturbing structure portion 4 has periodical changes in the depth of the first or second optical waveguide portion 1 or 2 due to the formation of electrodes, the uneven portion or the proton exchange, or the refractive index. It can be configured by the periodic change of.

In each of the above-mentioned examples, as shown in FIG. 11 which is a cross-sectional view taken along a plane crossing the light propagation direction, on the coupling portion where the first and second optical waveguide portions 1 and 2 are laminated, for example, Dielectric film 5 loaded on first optical waveguide 1
A pair of electrodes 20A and 20 is provided on both sides of the upper side and the upper side.
B is deposited and a variable DC voltage E _B is applied between these electrodes 20A and 20B. In this case, an electric field can be applied in the depth direction as schematically shown by the solid lines in FIG. 11 as the lines of electric force. Therefore, the effective refraction of the guided mode can be controlled by controlling the applied voltage E _B. You can change the rate.

Therefore, in this case, the phase matching condition between the 0th-order mode and the 1st-order mode can be substantially changed by controlling the voltage E _B , which allows the periodic refractive index disturbing structure portion 4 to change the phase matching condition. The wavelength λ ₀ converted between the first and second optical waveguide sections 1 and 2 can be shifted. Therefore, by applying this configuration to the above-mentioned wavelength band pass filter and wavelength band cut filter, it is possible to configure a frequency variable filter capable of varying the central wavelength to be transmitted or cut.

In this case, since the wavelength λ ₀ can be largely shifted even with a slight change in the refractive index in the depth direction, the wavelength selection central wavelength variable range becomes wide.

In the above-described embodiment, the loading type three-dimensional waveguide structure for loading the dielectric film 5 is used. However, as shown in FIG. 12, the first optical waveguide section 1 and the second optical waveguide section 1 are provided. Even if the optical waveguide section 2 is a three-dimensional embedded type three-dimensional waveguide, the same operation as described above can be performed.

Incidentally, in FIGS. 8 to 12, FIGS.
Portions corresponding to those in FIGS. 4 to 7 are designated by the same reference numerals, and duplicate description will be omitted.

Also in the above-mentioned embodiment shown in FIG. 4 and subsequent figures, the first and second optical waveguide sections 1 and 2 can be proton exchange waveguides or have a dielectric film structure. You can also

In the above-mentioned example, the substrate 1 made of LN is used.
However, it is not limited to LN, but LiTaO ₃ (LT: that is, LiTa _x N described above is used.
b _1-x O ₃ in x = 1) can be similarly constructed by the substrate.

[0072]

As described above, in the configuration of the present invention, the two-layered waveguide sections of the first and second optical waveguide sections 1 and 2 having different refractive indexes are used to propagate the 0th-order and 1st-order modes. Since the multimode optical waveguide 3 is configured and the wavelength is selected by using the wavelength dependence of the mode conversion by the periodic refractive index perturbation structure 4, the wavelength can be reliably selected with a simple structure such as a bandpass filter or a band cut filter. You can configure filters.

Further, when the wavelength selection band is made variable as described above, an optical waveguide type wavelength selection device having a wide variable range of the center wavelength can be manufactured.

Furthermore, for example, LN or LiTaO ₃ (LT)
In an optical waveguide type wavelength selecting device using such as a substrate, an optical waveguide type wavelength selecting device with little optical damage and excellent optical power durability can be constructed.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a device of the present invention.

FIG. 2 is a schematic perspective view of an example of the device of the present invention.

FIG. 3 is a manufacturing process diagram of an example of the device of the present invention. A is a sectional view in one step. B is a sectional view in one step. C is a cross-sectional view in one step. D is a sectional view in one step.

FIG. 4 is a schematic perspective view of an example of the device of the present invention.

FIG. 5 is a schematic perspective view of an example of the device of the present invention.

FIG. 6 is a schematic perspective view of an example of the device of the present invention.

FIG. 7 is a schematic perspective view of an example of the device of the present invention.

FIG. 8 is a schematic perspective view of an example of the device of the present invention.

FIG. 9 is a schematic sectional view of an example of the device of the present invention.

FIG. 10 is a schematic sectional view of an example of the device of the present invention.

FIG. 11 is a schematic sectional view of an example of the device of the present invention.

FIG. 12 is a schematic sectional view of an example of the device of the present invention.

[Explanation of symbols]

 11 substrate 1 first optical waveguide 2 second optical waveguide 3 optical waveguide 4 periodic refractive index perturbation structure

Claims (12)

[Claims] 1. An optical waveguide having first and second end faces, the optical waveguide including a first optical waveguide section and a second optical waveguide section, and the optical waveguide being periodic with respect to a propagation direction of the optical waveguide. And a periodic refractive index disturbing structure portion that forms a refractive index disturbance, wherein the first optical waveguide portion has a refractive index higher than that of the second optical waveguide portion, and at least a part of An optical waveguide type wavelength selecting device, characterized in that it is in contact with the second optical waveguide portion. 2. A structure in which the periodic refractive index disturbing structure portion has a structure in which the refractive index periodically changes at the interface between the first optical waveguide portion and the second optical waveguide portion. The optical waveguide type wavelength selecting device described. 3. The periodic refractive index disturbing structure portion is the first
The optical waveguide type wavelength selection device according to claim 1, wherein the refractive index is periodically changed on the surface of the optical waveguide section. 4. An optical waveguide comprising a first optical waveguide section and a second optical waveguide section is formed on a substrate so that the second optical waveguide section is located on the substrate side, The second optical waveguide section has a refractive index higher than that of the substrate, and the first optical waveguide section has a refractive index greater than that of the substrate and the second optical waveguide section. The optical waveguide type wavelength selection device according to claim 1, wherein the periodic refractive index disturbing structure portion has a configuration in which the refractive index periodically changes at an interface between the second optical waveguide portion and the substrate. apparatus. 5. The optical waveguide type wavelength selection device according to claim 1, wherein the periodic refractive index disturbing structure portion has a configuration in which the refractive index is periodically changed by an electric field from an electrode. 6. The first and second optical waveguide sections are proton exchange waveguides, and claim 1,
The optical waveguide type wavelength selecting device according to 3, 4, or 5. 7. The first optical waveguide portion is a dielectric film,
The optical waveguide type wavelength selection device according to claim 1, 2, 3, 4, or 5, wherein the second optical waveguide portion is a proton exchange waveguide. 8. The optical waveguide type wavelength selection device according to claim 1, 2, 3, 4 or 5, wherein the first and second optical waveguide portions are dielectric films. 9. The optical waveguide is only the first optical waveguide portion on the first end face, and the optical waveguide is only the second optical waveguide portion on the second end face. The optical waveguide type wavelength selection device according to claim 1, 2, 3, 4, 5, 6, 7 or 8. 10. The optical waveguide on each of the first and second end faces is only the first optical waveguide portion, 1, 2, 3, 4, 5, 6, 7 or 8. An optical waveguide type wavelength selecting device according to. 11. The optical waveguide according to claim 1, wherein the optical waveguide is only a second optical waveguide portion on the first and second end faces. Optical waveguide type wavelength selector. 12. The substrate is LiTa _X Nb _1-x O
₃ (0 ≦ x ≦ 1), wherein
The optical waveguide type wavelength selection device according to 6, 7, 8, 9, 10 or 11.