JP2001330745A - Optical waveguide grating device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide grating device such as a band passing filter, a coupling and branching device and a dispersion compensator wherein temperature stability of a reflected central wavelength of a grating is improved and its manufacturing method. SOLUTION: In the optical waveguide grating device 1 wherein a clad layer 7 storing a core layer 5 is formed on a substrate 21 and the grating 2 is formed in at least a part of the core layer 5, the substrate 21 is the optical waveguide grating device 1 consisting of a material having a linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the core layer 5. Also, the clad layer 7 storing the core layer 5 is formed on the substrate 21 consisting of a material having a linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the core layer 5, and the grating 2 is formed in at least a part of the core layer 5 to obtain the optical waveguide grating device 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical waveguide grating device and a method of manufacturing the same, and more particularly, to an optical waveguide grating device such as a band-pass filter, a multiplexer / demultiplexer, a dispersion compensator, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in an ultra-high-speed wavelength division multiplexing communication system, with the advancement of a wavelength division multiplexing optical communication system, an optical multiplexer / demultiplexer for multiplexing / demultiplexing a wavelength multiplexed signal, a bandpass filter, and a dispersion compensator have been developed. There has been a growing demand for improved control techniques for the central wavelength of reflection.

FIG. 9 shows an example of a band-pass filter using a conventional waveguide grating device. Waveguide grating devices, as used herein, those having a function of reflecting light of a particular wavelength, the reflection center wavelength lambda _c is defined by the following equation (1). Here, N _eff is the effective refractive index of the grating, and Λ is the period of the grating.

(Equation 1)

In the band pass filter 10 shown in FIG.
The light input from port P1 is split by a 3 dB coupler for 2 minutes.
It is forked. Grating reflection center wavelength λ_cEquals
Wavelength light, that is, the signal light S (λ₁) Is a grating
Is reflected by the port P, and is multiplexed again by the 3 dB coupler, and the port P
2 output. Grating reflection center wavelength λ _c
Light with a wavelength different from that of the
And output from ports P3 and P4. in this way
Then, the band-pass filter 10 of FIG.
Only the signal light can be extracted from port P2.
You.

FIG. 10 shows an example of a multiplexing / demultiplexing circuit 20 using a waveguide grating device. In the conventional multiplexing / demultiplexing circuit 20 shown in FIG. 10, for example, signals (S (λ ₁ ), S
(Λ ₂ ), S (λ ₃ ),...) Are input from the port P1, and only the signal light of a specific wavelength (in FIG. 10, S
(Λ ₁ )) is reflected by the grating and output from the port P2 (demultiplexing). Signal light of other wavelength (S
(Λ ₂ ), S (λ ₃ ),...) Are output from the port P4. The port signal light S of a specific wavelength input from P3 (lambda ₁₎ (light having a wavelength of lambda ₁₎ is output after being reflected by the grating from the port P4 (multiplexing).

[0006] The SiO ₂ optical waveguide device has many advantages such as low loss and good compatibility with an optical fiber cable, and is a device suitable for an optical communication system. FIG. 11A is a sectional view taken along the waveguide of the multiplexing / demultiplexing circuit 20 using the optical waveguide grating device of FIG. 10, and FIG. 11B is a sectional view perpendicular to the waveguide. It is. The dotted line shown in FIG. 11B indicates the boundary between the under cladding layer 4 and the over cladding layer 6 in the cladding layer 7. Usually, the optical waveguide is composed of a core layer 5 made of a SiO ₂ material and a clad layer 7 surrounding the core layer 5.
(Under cladding layer 4 and over cladding layer 6). In consideration of the matching with the optical fiber, the size of the under cladding layer 4 is about 20 μm, the cross section of the core layer 5 is about 6 × 6 to 8 × 8 μm, and the thickness of the over cladding layer 6 is about 20 μm. Are used. Further, the core layer 5 has a cladding layer 7 for guiding light.
It is manufactured so that the refractive index becomes higher by about 0.3 to 2% than that of the above.

The manufacturing process of the conventional SiO ₂ based waveguide is as follows.
(1) a step of forming an under cladding layer 4 on a substrate 3, (2) a step of forming a core layer 5, (3) a step of patterning a mask by photolithography, and (4) a dry or wet process. It comprises a step of forming the core layer 5 by etching and (5) a step of forming the over cladding layer 6 covering the core layer 5.

Next, a method for manufacturing an optical waveguide grating will be described. As a typical method of manufacturing an optical waveguide grating, a method utilizing a photo-induced refractive index change can be cited. Note that the light-induced refractive index change is a phenomenon in which the refractive index changes when an SiO ₂ -based waveguide to which germanium is added is irradiated with ultraviolet light.

Specifically, when two ultraviolet lights interfere with each other on a waveguide to form an interference fringe, a refractive index change corresponding to the period of the interference fringe occurs, and a waveguide grating is manufactured. The change in the refractive index due to this is as small as about 0.001, but one period of the interference fringes is very small, about 500 nm. A waveguide grating can be manufactured, and a reflectance of approximately 100% can easily be obtained at a reflection center wavelength.

[0010] In the optical waveguide grating manufactured as described above, there is a certain variation in the reflection center wavelength of the grating due to manufacturing variations in the grating period. Also, in the fabrication of the grating, if the intensity of the ultraviolet light or the irradiation time is increased, or if the waveguide grating is fabricated to be inclined from the direction perpendicular to the traveling direction of the light in the waveguide due to conditions such as settings, the reflection center wavelength is increased. growing. Therefore, a step of adjusting the reflection center wavelength may be required. Conventionally, after the waveguide grating is manufactured, the reflection center wavelength is measured, and if the desired reflection center wavelength is different from the desired reflection center wavelength, the waveguide grating is further subjected to ultraviolet light. There is a method of adjusting the reflection center wavelength by irradiating light (Japanese Patent Application Laid-Open No. 9-288205).
Further, there is a method of performing a heat treatment in order to suppress a temporal change of the reflection center wavelength (Japanese Patent Application Laid-Open No. H10-339821).

The effective refractive index N _eff of an optical waveguide using a SiO ₂ material changes with temperature, and the central reflection wavelength λ _c also changes according to _Equation 1 as shown in FIG. Normally, a grating fabricated on a SiO ₂ -based waveguide has a refractive index that changes at a rate of 0.01 nm / ° C. However, the problem that the reflection center wavelength changes due to temperature change is a problem of the material itself. Conventionally, the temperature is controlled by using a Peltier element or the like, and the optical medium has a refractive index with a temperature coefficient opposite to that of the waveguide. Is coated on the waveguide (Japanese Patent Laid-Open No. Hei 10-186167) to prevent the temperature change of the reflection center wavelength.

A report by Arai et al. On "Temperature characteristic compensation of waveguide-type Add / Drop filter (C-3-98)" at the 1999 IEICE General Conference described a quartz substrate on which a waveguide was formed. A method of generating a concave-shaped warp due to a difference in thermal expansion coefficient between a quartz substrate and an aluminum plate by using a structure in which an aluminum plate having a high thermal expansion coefficient is adhered to the bottom of an aluminum plate with an adhesive has been proposed. By controlling the amount of distortion, the reflection center wavelength of the grating cancels out the change in the reflection center wavelength due to the temperature change in the refractive index of quartz, thereby slightly reducing the temperature change in the reflection center wavelength.

[0013]

However, the method of re-irradiating the waveguide grating with ultraviolet light or the method of performing heat treatment has a problem that it takes a long time for adjustment and cannot be manufactured at low cost. Further, these are adjustment methods performed immediately after manufacturing, and are not suitable for compensating for a temperature change under a use environment. On the other hand, as a structure for reducing the temperature change of the reflection center wavelength, a structure for controlling the temperature using a Peltier element or the like requires a device for temperature control, and there is a problem that the entire device is enlarged. In a structure in which an optical medium having a refractive index having a temperature coefficient opposite to that of the refractive index of the waveguide is coated on the waveguide, there is a problem that the structure is complicated and the manufacturing time is long. .

In a structure in which a metal plate having a larger coefficient of thermal expansion than the substrate is attached to the lower surface of the substrate with an adhesive, the bonding between the substrate and the aluminum plate is based on the adhesive.
This adhesive layer absorbs stress strain or generates a gap between the substrate and the aluminum plate, so that sufficient stress cannot be transmitted to the grating, and it has been difficult to improve the temperature dependency.

[0015]

An optical waveguide grating device according to the present invention comprises an optical waveguide formed by forming a clad layer for accommodating a core layer on a substrate and forming a grating on at least a part of the core layer. A grating device, wherein the substrate is made of a material having a linear thermal expansion coefficient larger than a linear thermal expansion coefficient of the core layer.

An optical waveguide grating device according to the present invention is an optical waveguide grating device in which a clad layer for accommodating a core layer is formed on a substrate, and a grating is formed on at least a part of the core layer.
An upper layer made of a material having a linear thermal expansion coefficient smaller than that of the core layer is formed on the cladding layer.

An optical waveguide grating device according to the present invention is an optical waveguide grating device in which a clad layer for accommodating a core layer is formed on a substrate, and a grating is formed on at least a part of the core layer.
The substrate is composed of a material having a linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the core layer, and an upper layer made of a material having a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the core layer on the cladding layer. Is formed.

The optical waveguide grating device may further comprise at least one intermediate layer made of a material having a linear thermal expansion coefficient selected between a linear thermal expansion coefficient of the substrate and a linear thermal expansion coefficient of the core layer. Is further formed between the substrate and the cladding layer.

Further, in the above-mentioned optical waveguide grating device, the substrate has a thickness d of the substrate and a change amount dλ / of a reflection center wavelength of the grating with respect to the temperature.
In relation to dT, the temperature change dλ / dT is −
It is characterized by having a thickness adjusted in advance so as to be in a range of 0.010 nm / ° C to 0.010 nm / ° C.

Still further, in the above-mentioned optical waveguide grating device, the core layer has at least one selected from the group consisting of Ge, Ti, Zr, Al, B, P, and F, mainly composed of SiO ₂ -based glass. It is characterized by being made of SiO ₂ glass containing one or more additional elements.

Further, in the optical waveguide grating device, the grating formed on at least a part of the core layer is formed by irradiating ultraviolet light to change a refractive index of at least a part of the core layer. It is characterized by having.

A method of manufacturing an optical waveguide grating device according to the present invention includes the steps of: forming a clad layer for accommodating a core layer on a substrate; and forming a grating on at least a part of the core layer. Wherein the substrate is made of a material having a linear thermal expansion coefficient larger than that of the core layer.

A method of manufacturing an optical waveguide grating device according to the present invention includes the steps of: forming a cladding layer for accommodating a core layer on a substrate; and forming a grating on at least a part of the core layer. The method of claim, wherein on the cladding layer,
The method may further include forming an upper layer made of a material having a linear thermal expansion coefficient smaller than a linear thermal expansion coefficient of the core layer.

[0024] A method for manufacturing an optical waveguide grating device according to the present invention is a method for manufacturing an optical waveguide grating device, comprising the step of forming a clad layer for accommodating a core layer on a substrate. Forming a top layer made of a material having a coefficient of linear thermal expansion larger than the coefficient of linear thermal expansion of the layer, and a material having a coefficient of linear thermal expansion smaller than the coefficient of linear thermal expansion of the core layer on the cladding layer. It is further characterized by including.

Further, in the method of manufacturing the optical waveguide grating device, before forming the cladding layer on the substrate, the linear thermal expansion coefficient between the substrate and the core layer may be changed. The method may further include forming at least one intermediate layer made of a material having a selected coefficient of linear thermal expansion between the substrate and the cladding layer.

Further, in the method of manufacturing the optical waveguide grating device, the substrate may be configured such that the temperature change amount dλ / dT is a relation between the thickness of the substrate and the change amount dλ / dT of the reflection center wavelength of the grating with respect to the temperature.
It is characterized by having a thickness adjusted in advance so that / dT is in the range of -0.010 nm / ° C to 0.010 nm / ° C.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to facilitate understanding of the present invention, the present invention will be described with reference to the following embodiments.

Embodiment 1 As shown in FIG. 1A, the optical waveguide grating device according to the first embodiment of the present invention has an optical waveguide grating 2 on a substrate 21 made of a material having a larger thermal expansion coefficient than the SiO ₂ glass of the core layer 5. Is formed.

FIG. 1A is a cross-sectional view taken along the waveguide when a material having a higher linear thermal expansion coefficient than that of the SiO ₂ glass of the core layer 5 is used for the substrate 21. 4) is a schematic view in which the substrate 21 and the optical waveguide grating 2 formed thereon are stressed due to a difference in their linear thermal expansion coefficients due to a temperature rise, and the core layer 5 including the grating 2 is bent like a bimetal. It is.

The optical waveguide grating device according to the first embodiment includes a core layer 5 and a cladding layer 7 on a substrate 21.
(Under cladding layer 4 and over cladding layer 6). As the substrate 21, an Al substrate 21 (purity: 99% or more) having a thickness of 0.3 mm and a higher linear thermal expansion coefficient than the SiO ₂ glass of the core layer 5 is used. The under cladding layer 4 formed on the substrate 21 is made of SiO ₂ -based glass (37.5 wt% as Si and 7.8 wt% as B) having a thickness of 15 to 20 μm. The core layer 5 formed on the under cladding layer 4 is made of 6 μm thick SiO ₂ glass (50 wt% or less for Si, 15 wt% or less for Ge, and 5 wt% or less for B). The over cladding layer 6 formed on the core layer 5 has a thickness of 15 to 20 μm.
It is made of iO ₂ -based glass (37.5 wt% as Si, 7.8 wt% as B). The respective composition ratios are adjusted so that the refractive index difference between the core layer 5 and the cladding layer 7 is about 0.7%.

In the optical waveguide grating device according to the first embodiment, when the temperature rises, the substrate 2
1 and the core layer 5 have different coefficients of linear thermal expansion, so that the amounts of thermal expansion are different. A stress is generated due to the difference in the amount of thermal expansion, and the grating 2
The core layer 5 containing 撓 is bent to reduce the period Λ of the grating 2 (FIG. 1B). When the temperature rises, the grating 2 is bent so that the grating 2
, The reflection center wavelength λ _c of the grating 2 is shifted to the shorter wavelength side according to the equation 1, and the temperature change of the reflection center wavelength of the grating 2 due to the temperature change of the refractive index of the SiO ₂ based material is compared with each other. It offsets and improves temperature stability.

[0032] describing the specific effect of reducing the temperature change of the reflection center wavelength lambda _c of the grating 2 below. FIG.
As shown in FIG. 2, near the room temperature, the reflection center wavelength λ _c increases as the temperature rises. If the temperature rises, there is a difference in the coefficient of linear thermal expansion between the substrate 21 and the core layer 5, so that the amounts of thermal expansion are different. Stress is generated due to the difference in the amount of thermal expansion, and the core layer 5 including the grating 2
Is bent to reduce the period Λ of the grating 2. Smaller in accordance with the number 1 reflection center wavelength lambda _c by the period of the grating 2 lambda is reduced. Thus, it is possible to suppress the increase of the reflection center wavelength lambda _c due to temperature rise. On the other hand, it can be the time of temperature drop can suppress the reduction of the reflection center wavelength lambda _c by opposite effects in the case of temperature rise, to compensate for the temperature change of the reflection center wavelength lambda _c.

Hereinafter, each component of the optical waveguide grating filter 10 which is the optical waveguide grating device according to the first embodiment will be described with reference to FIG.

As the optical waveguides 11 and 12, for example, a pair of SiO ₂ -based optical waveguides doped with germanium is formed on the substrate 21 so as to be line-symmetric with each other. A part of the two optical waveguides 11 and 12 is brought close to each other so that 3
The dB coupler 15 is formed. Optical waveguide grating 1
For example, by forming interference fringes using ultraviolet light, the refractive indices 3 and 14 are formed in a part of the optical waveguides 11 and 12 by changing the refractive index at a predetermined period. The optical waveguide gratings 13 and 14 are formed on the respective optical waveguides 11 and 12 so as to be line-symmetric with each other. Note that the fiber connector 16 for external connection is connected to the optical waveguide 1.
It may be connected to the ends of 1 and 12 and fixed to the end of the substrate.

In the optical waveguide grating filter 10 of the first embodiment, the light input from the port P 1 is split into two by the 3 dB coupler 15. Of the two branched optical signal light corresponding to the reflection center wavelength lambda _c of the optical waveguide grating 13, 14 optical waveguide grating 1
The light is reflected at 3, 14 and multiplexed again by the 3 dB coupler 15 and output from the port P2. Grating 13, 1
Light other than the reflection center wavelength of 4, ie, noise, passes through the gratings 13 and 14 and is output from the ports P3 and P4. Thus, the optical waveguide grating filter 10 has a function of cutting noise and extracting only signal light having a predetermined reflection center wavelength.

In the optical waveguide grating filter 10 according to the first embodiment, the under cladding layer 4, the core layer 5, and the over cladding layer 6 are made of SiO ₂ glass, and the composition of the core layer 5 is as follows. SiO
₂ as a main component, preferably containing 15 wt% or less of Ge, and preferably containing 5 wt% or less of B. The core layer 5 may include Ti, Zr, Al, B, P, and F. The composition of the under cladding layer 4 is mainly composed of SiO ₂ , and may include B, P, F, and Ge. The composition of the over cladding layer 6 is mainly composed of SiO ₂ , and may include B, P, F, and Ge. The under cladding layer 4 and the over cladding layer 6 preferably have the same composition as the cladding layer 7 surrounding the core layer 5.

As the substrate 21, SiO 2 of the core layer 5 is used._Twosystem
Glass (linear thermal expansion coefficient: 5.50 × 10^-7° C^-1)than
Use of a material with a large coefficient of linear thermal expansion
it can. The difference between the linear thermal expansion coefficients of the substrate 21 and the core layer 5 is large.
If it is too large, the optical waveguide grating device will be distorted
May occur, and the core layer 5 may be damaged. _Two
System glass (linear thermal expansion coefficient: 5.50 × 10^-7° C^-1) To
Then 10^ThreeIt is preferred that the coefficient of linear thermal expansion be within
New More preferably SiO 2_Two2 times that of base glass
It has a linear thermal expansion coefficient within the above range and within 100 times
Material. Specifically, a metal substrate is used as the substrate 21.
Al (linear thermal expansion coefficient (hereinafter abbreviated by the same)):
2.37 × 10^-Five° C^-1), Zn (3.30 × 10
^-Five° C^-1), W (4.50 × 10^-6° C^-1), Si (3.2
0x10^-6° C^-1) And the like can be used.
Is the alumina Al_TwoO_Three(7.50 × 10^-6° C^-1),
Magnesium oxide MgO (1.0 × 10^-Five° C^-1), Oxidation
Zirconium ZrO_Two(1.0 × 10^-Five° C^-1),Titanium
Barium acid BaTiO_Three(9.4 × 10^-6° C^-1) Etc.
Can be.

In the optical waveguide grating filter 10 of the first embodiment, the grating 13 is formed by the temperature change of the refractive index of the SiO ₂ optical waveguide due to the change of the surrounding temperature.
The change in the temperature of the reflection center wavelength at 14 can be reduced, and a stable filter characteristic with respect to the temperature change can be obtained without power consumption accompanying temperature control or the like. Also, a significant cost reduction can be expected as compared with a structure in which temperature control is performed using a conventional Peltier element or the like. Further, in comparison with the conventional structure in which a metal plate having a larger linear thermal expansion coefficient than the substrate is bonded to the lower surface of the substrate, the under cladding layer 4, the core layer 5, and the over cladding layer 6 are formed on the substrate 21 by the direct CVD method. As a result, the adhesiveness is excellent and the stress is transmitted uniformly, so that the temperature change of the reflection center wavelength is effectively compensated. Thereby, the dispersion amount variable equalizer, the band-pass filter, the ADM
(Add-Drop Multiplexer / Demultiplexer) As an optical waveguide for filter applications, it can reduce the temperature change of the reflection center wavelength of the optical waveguide gratings 13 and 14 due to the ambient temperature change, and can realize a stable filter characteristic against the temperature change. .

FIG. 3 shows an example of a manufacturing process for the optical waveguide grating filter according to the first embodiment. The optical waveguide grating filter according to the first embodiment has a CV
It is preferable to manufacture by the method D (chemical vapor deposition method). The manufacturing process of the optical waveguide grating filter in the CVD method is as follows. (A) First, the under cladding layer 4 is formed on the substrate 21 by the plasma CVD method, and the core layer 5 is formed on the under cladding layer 4 by the plasma CVD method. (B) Next, after performing a heat treatment at a temperature (800 to 1200 ° C.) lower than the softening temperature of the under cladding layer 4 and the core layer 5, a Cr film 25 for a mask (metal film) is formed on the core layer 5 by sputtering. ) Is formed, (c) a resist layer 26 is formed on the Cr film 25, (d) the resist layer 26 is patterned by photolithography, and (e) the Cr film 25 is then dry (wet) etched. Is patterned. (F) Then, using the patterned Cr film 25 as a mask, the core layer 5 is processed into a convex shape by RIE (Reactive Ion Etching). (G) Next, the Cr film 25 on the core layer 5 is removed by wet etching. (H) Next, the over cladding layer 6 on the core layer 5 which is machined into a convex shape formed by TEOS-O ₃ CVD method, then, after heat treatment at 800 to 1200 ° C., cut, polished.

In the above process, the under cladding layer 4, the core layer 5, and the over cladding layer 6 can be formed by a CVD method. Specifically, as a CVD method, a plasma CVD method, TEOS-O ₃ CVD method, reduced pressure CVD method, can be formed by any method such as atmospheric pressure CVD. Since the under cladding layer 4, the core layer 5, and the over cladding layer 6 are formed on the substrate by the CVD method, the adhesion between the substrate 21 and the core layer 5 and the like is excellent, and the stress from the substrate 21 is easily transmitted. ing.

FIG. 4 shows a plasma CVD apparatus 30 used for manufacturing the optical waveguide grating filter of the first embodiment.
FIG. This apparatus is a capacitively coupled plasma CVD apparatus 30 using parallel plate type electrodes, 31 is an upper shower electrode, 32 is a high frequency electrode (hereinafter abbreviated as RF electrode), 33 is a matching circuit, and 34 is a high frequency power supply. ,
35 to 37 are each raw material containers, 38 is an oxygen gas supply port,
39 to 42 are mass flow controllers, 43 is a reaction vessel, and 46 is an evacuation system. A matching circuit 33 and a high-frequency power supply 34 are connected to the RF electrode 32. The substrate 44 on which the film is to be formed is placed on the RF electrode 32 and heated to several hundred degrees Celsius by a heater below the RF electrode 32. The upper shower electrode 31 is also heated to several hundred degrees Celsius by a separately provided heater. The upper shower electrode 31 has a shower structure in which the inside is hollow and has a large number of holes on the electrode facing surface in order to uniformly blow gas between the parallel plate electrodes.

The high frequency power supply 34 has a frequency of 13.5.
Use a 6MHz one. Using this apparatus, a gas is introduced into the reaction vessel 43 from the raw material vessels 35 to 37 and the oxygen gas supply port 38, and the undercladding layer 4, the core layer 5, and the overcladding layer 6 are formed under reduced pressure. Do.

The raw material for forming each layer is S
Alkoxides such as i and Ge can be used. Specifically, tetraethoxysilane Si (OC ₂ H ₅ ) ₄ is used as a material for forming the under cladding layer 4, and tetraalkoxy is used as a material for forming the core layer 5. Ethoxysilane Si (OC
₂ H ₅ ) ₄ , tetraethoxygermanium Ge (OC
₂ H ₅ ) ₄ and triethoxy boron B (OC ₂ H ₅ ) ₃ , and tetraethoxysilane Si (OC ₂ H ₅ ) ₄ and triethoxy boron B (OC ₂
Can be used H _{5) 3.}

The grating 2 was formed by causing two ultraviolet lights to interfere with each other to form an interference fringe on the waveguide and causing a change in the refractive index corresponding to the period of the interference fringe to produce a grating. The wavelength of the ultraviolet light used for forming the grating 2 is not particularly limited, but is preferably in the range of 100 to 400 nm from a practical viewpoint, and is preferably 150 to 38 nm.
The range of 0 nm is more preferable.

Embodiment 2 The optical waveguide grating device according to the second embodiment of the present invention
Before the core layer 5 is formed on the Al substrate 21 (having a purity of 99% or more and a thickness of 0.3 mm) having a larger linear thermal expansion coefficient than that of the iO ₂ -based glass, the thickness is about several tens nm on the Al substrate 21 in advance. Of the thermal oxide film (intermediate layer) 23, and then the under cladding layer 4,
The core layer 5 and the over cladding layer 6 were formed. in this case,
The Al thermal oxide film 23 has a coefficient of linear thermal expansion between the SiO ₂ glass of the core layer 5 and the Al substrate 21 and serves as a buffer.

FIG. 5 is a cross-sectional view taken along the optical waveguide of the optical waveguide grating device according to the second embodiment. As shown in FIG. 5, in the optical waveguide grating device according to the second embodiment, the Al substrate 2 is provided on the Al substrate 21 having a larger linear thermal expansion coefficient than the SiO ₂ glass of the core layer 5.
1 and the core layer 5 are provided with a thermal oxide film 23 of Al having an intermediate linear thermal expansion coefficient.
It is possible to prevent the occurrence of cracks due to internal strain of the optical waveguide, which can occur when the difference in linear thermal expansion coefficient between the _second system glass and the Al substrate 21 is extremely large. In this case, the intermediate layer 23 plays a role of a buffer for relieving a large stress applied to the core layer 5 and the clad layer 7, and prevents the entire optical waveguide from being damaged by distortion. Further, by providing the intermediate layer 23, mutual ion diffusion between the substrate 21 and the clad layer 7 can be prevented.

In the second embodiment, the case where only one intermediate layer 23 is provided has been described. However, the present invention is not limited to this, and one or more intermediate layers 23 can be provided.
In this case, it is preferable that the intermediate layers 23 are arranged such that the coefficient of linear thermal expansion decreases from the side closer to the substrate 21 to the side closer to the core layer 5. By providing the arrangement of the plurality of intermediate layers 23 between the substrate 21 and the core layer 5 made of a material having a large linear thermal expansion coefficient, even when the linear thermal expansion coefficients of the substrate 21 and the core layer 5 are significantly different. Deflection can be caused without causing distortion. In addition, even in the case of a single intermediate layer, the composition can be gradually changed to gradually change the linear thermal expansion coefficient. These may be combined. Also, the middle layer 2
3 is preferably formed easily on the substrate 21. For example, when the Al substrate 21 is used, the thermal oxide film 23 of Al is preferable as the intermediate layer.

The optical waveguide grating device according to the second embodiment configured as described above includes a variable dispersion amount equalizer,
For optical waveguides for bandpass filters and ADM filters, reduce the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the optical waveguide due to the ambient temperature change, and obtain a stable filter characteristic against the temperature change. Can be.

Embodiment 3 The optical waveguide grating device according to the third embodiment, which is one embodiment of the present invention, uses a substrate 21 made of a material having a larger coefficient of thermal expansion than the SiO ₂ glass of the core layer 5 as in the first embodiment. To form an optical waveguide grating device.

FIGS. 6 and 7 show the case where the optical waveguide gratings 13 and 14 are provided on the substrate 21 made of a material having a higher linear thermal expansion coefficient than the SiO ₂ glass of the core layer as in the first embodiment (total thickness). 56 μm: under cladding layer 25
μm, core layer 6 μm, over cladding layer 25 μm)
Type of substrate 21 material, substrate thickness (log scale), and temperature change amount (dλ / dT) of reflection center wavelength λ _c at room temperature
6 is a graph showing a result obtained by simulating the relationship with. FIG. 6 shows a case where a metal is used as the material of the substrate 21. The mark ● represents the case where aluminum (Al) is used as the substrate material, and the mark Δ represents the case where tungsten (W) is used as the substrate material.
The symbol ▲ indicates the temperature change amount (dλ / dT) of the reflection center wavelength in the case where silicon (Si) is used as the substrate material, and the mark 場合 indicates the characteristic in the case where zinc (Zn) is used as the substrate material.

FIG. 7 shows the type of the substrate material, the substrate thickness (log scale), and the temperature change amount (dλ / d) of the reflection center wavelength λ _c at room temperature when a metal oxide is used as the material of the substrate 21.
12 is a graph showing a result obtained by simulation of a relationship with T). The mark ● indicates the case where alumina (Al ₂ O ₃ ) is used as the substrate material, the mark Δ indicates the case where magnesium oxide (MgO) is used as the substrate material, and the mark ▲ indicates the zirconium oxide (Zr).
When O ₂ ) is used as the substrate material, the symbol Δ indicates the temperature change (dλ / dT) characteristic of the reflection center wavelength in each case where barium titanate (BaTiO ₃ ) is used as the substrate material.

From the results of FIG. 6 and FIG.
The substrate 2 is made of a material having a larger linear thermal expansion coefficient than that of the O ₂ glass.
In the case of using 1, the amount of temperature change (dλ / dT) of the reflection center wavelength of the grating can be made closer to dλ / dT = 0 by adjusting the substrate thickness. That is, the temperature change amount (dλ / d) of the reflection center wavelength of the grating in the SiO ₂ optical waveguide grating device.
dT) can be theoretically made substantially close to 0, and the temperature dependency can be substantially eliminated.

Here, the thickness of the substrate 21 used is
Any strength can be used as long as it is practical, preferably 0.0
It is 5 mm or more, more preferably 0.1 mm or more.

In the optical waveguide grating device according to the third embodiment, the amount of change dλ / dT with respect to the temperature of the reflection center wavelength of the gratings 13 and 14 is −0.0.
It is preferably in the range of 10 nm / ° C. to 0.010 nm / ° C., and more preferably in the range of −0.005 nm / ° C. to 0.005 nm / ° C. More preferably-
Desirably, the range is 0.002 nm / ° C to 0.002 nm / ° C.

Optical waveguide gratings are respectively formed on an Al substrate (purity 99% or more, thickness 0.3 mm) 21 and an Al ₂ O ₃ substrate 21 (purity 99% or more, thickness 0.3 mm) by a CVD method. Then, as a result of measuring the temperature change amount (dλ / dT) of the reflection center wavelength, 0.006 nm / ° C.
0.008 nm / ° C. is obtained, and the Si substrate (thickness: 0.3 m
m) The amount of change in temperature of the reflection center wavelength (0.
009 nm / ° C) and 0.003 nm /
° C, 0.001 nm / ° C.

As described above, by adjusting the type and thickness of the substrate 21, the optical waveguide grating 1
It is possible to effectively compensate for the temperature change of the reflection center wavelengths 3 and 14.

Embodiment 4 FIG. Embodiment 4 according to the present invention
As shown in FIG. 8, the optical waveguide grating device is formed on a SiO ₂ substrate (thickness: 1 mm) 3 by a CVD method.
15 to 20 μm thick SiO ₂ glass (Si as 3
An under cladding layer 4 made of 7.5 wt% (7.8 wt% as B) and a 6 μm thick SiO ₂ glass (Si
50 wt% or less, Ge as 15 wt% or less, B
5% by weight or less), a thickness of 15 to 2
0 μm SiO ₂ glass (37.5 wt% as Si)
%, B is 7.8 wt%), and further, S having a smaller linear thermal expansion coefficient than the SiO ₂ glass of the core layer 5 is formed on the upper surface of the over cladding layer 6.
An upper layer 22 made of iO ₂ —TiO ₂ is formed.

In the optical waveguide grating device of the fourth embodiment, the upper layer 22 made of a material having a smaller thermal expansion coefficient than that of the SiO ₂ glass of the core layer 5 is formed on the upper surface of the over cladding layer 6 so that the grating 2 is formed.
When the temperature rises, a warp is generated like a bimetal, the grating is bent by the amount of warp, the period の of the grating 2 is reduced according to the amount of warp, and the reflection center wavelength λ is , The temperature stability of the reflection center wavelength due to the temperature change of the refractive index of the SiO ₂ -based material is offset each other, thereby compensating the temperature stability.

In the optical waveguide grating device according to the fourth embodiment, as the upper layer 22 formed on the upper surface of the over cladding layer 6, the core layer 5 is made of SiO ₂ glass (linear thermal expansion coefficient: 5.50 × 10 ^{−). A} material made of a material having a smaller linear thermal expansion coefficient than ⁷ ° C. ^-1 ) can be used. In this case, a material having a linear thermal expansion coefficient having an opposite sign can be used. Specifically, SiO ₂ —TiO ₂ glass (linear thermal expansion coefficient: −3.0 × 10 ⁻⁸ ° C. ⁻¹ ), SiO ₂ −
Al ₂ O ₃ —Cu ₂ O-based glass (linear thermal expansion coefficient: 4.8 ×)
10 ^-7 ° C ^-1 ) and the like. These can be formed by a gas phase synthesis method such as a sol-gel method or an RF sputtering method.

When the upper layer 22 made of a material having a smaller linear thermal expansion coefficient than that of the SiO ₂ glass of the core layer 5 is provided on the overcladding layer 6, the upper layer 22 has two or more linear thermal expansion coefficients different from each other in a stepwise manner. It may be composed of layers.
In this case, it is preferable to adopt a configuration in which the upper portion of the upper layer 22 and the lower portion near the core layer 5 are made to gradually approach the linear thermal expansion coefficient of the core layer in a stepwise manner. Thereby, it is possible to prevent the occurrence of cracks due to internal strain of the optical waveguide, which may occur when a material having a very large linear thermal expansion coefficient difference from the SiO ₂ glass of the core layer 5 is used as a material forming the upper layer 22. it can.

In the optical waveguide grating device according to the fourth embodiment, after the upper layer 22 made of a material having a smaller linear thermal expansion coefficient than that of the SiO ₂ glass of the core layer 5 is provided on the cladding layer 7, At least a part is provided with a grating. When heated at a high temperature, the formed grating 2 may disappear, so it is preferable to provide the upper layer 22 before forming the grating 2. In the optical waveguide grating device according to the fourth embodiment, the upper layer 22 is provided over the entire upper surface of the cladding layer 7.
_The upper layer 22 made of a material having a smaller linear thermal expansion coefficient than that of the _second glass may be provided in a range including at least the upper surface of the portion of the core layer where the grating 2 is provided.

The optical waveguide grating device according to the fourth embodiment is used as an optical waveguide for variable dispersion equalizers, band-pass filters, and ADM filters, because of the change in the refractive index of the optical waveguide due to a change in ambient temperature due to a change in ambient temperature. A change in temperature of the reflection center frequency can be reduced, and a stable filter characteristic can be realized with respect to a change in temperature.

[0063]

As described above in detail, according to the optical waveguide grating device of the present invention, since the substrate is made of a material having a higher linear thermal expansion coefficient than that of the SiO ₂ -based glass of the core layer, the temperature change Occurs, there is a difference in the coefficient of linear thermal expansion between the substrate and the core layer, and thus the amounts of thermal expansion are different. Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 By shifting the temperature, the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ -based material can be offset each other to improve the temperature stability.

Further, it is possible to reduce the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ optical waveguide due to the ambient temperature change without the power consumption accompanying the temperature control or the like. Stable filter characteristics can be obtained. As a result, a significant cost reduction can be expected as compared with a structure in which temperature control is performed using a conventional Peltier element or the like. Also, compared to the conventional structure in which a metal plate having a higher linear thermal expansion coefficient than the substrate is bonded to the lower surface of the substrate,
Since the core layer and the cladding layer are formed directly on the substrate, the adhesion is excellent and the stress is transmitted uniformly, so that the temperature change of the reflection center wavelength is effectively compensated. As a result, as an optical waveguide for variable dispersion equalizers, band-pass filters, and ADM filters, the temperature change of the reflection center wavelength of the optical waveguide grating due to the ambient temperature change is reduced, and the filter characteristics are stable against temperature change. Can be realized.

According to the optical waveguide grating device of the present invention, since the upper layer is made of a material having a smaller linear thermal expansion coefficient than the SiO ₂ glass of the core layer, when the temperature changes, the upper layer and the core are Because there is a difference in the coefficient of linear thermal expansion of each of the layers, the amount of thermal expansion of each differs.
Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 Shift, SiO ₂
The temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the system material can be mutually offset to improve the temperature stability. Further, since the upper layer plays a role of a protective film of the optical waveguide grating device, a highly reliable optical waveguide grating device can be obtained.

According to the optical waveguide grating device of the present invention, the substrate is made of a material having a higher linear thermal expansion coefficient than that of the core layer SiO ₂ -based glass, and the upper layer is formed of the core layer SiO ₂ -based glass. Since a material having a small coefficient of thermal expansion is used, if a temperature change occurs, there is a difference in the coefficient of linear thermal expansion between the substrate and the core layer, and between the core layer and the upper layer. The amount is different. Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 By shifting the temperature, the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ -based material can be offset each other to improve the temperature stability.

In the above case, the substrate is made of SiO ₂ of the core layer.
Since a material having a higher linear thermal expansion coefficient than that of the base glass is used, and a material having a lower linear thermal expansion coefficient than the SiO ₂ glass of the core layer is used for the upper layer, the material from both below and above the core layer is used. The stress allows the grating of the core layer to be smoothly bent.

According to the optical waveguide grating device of the present invention, the intermediate layer made of a material having a linear thermal expansion coefficient between the substrate and the core layer is provided between the substrate and the clad layer. It is possible to prevent the occurrence of cracks due to internal strain of the optical waveguide, which can occur when the difference in linear thermal expansion coefficient between the SiO ₂ -based glass of the layer and the substrate is extremely large. In this case, the intermediate layer plays a role of a buffer for relieving a large stress applied to the core layer and the clad layer, thereby preventing damage to the entire optical waveguide due to distortion. Further, by providing the intermediate layer, mutual ion diffusion between the substrate and the cladding layer can be prevented.

Further, according to the optical waveguide grating device of the present invention, the temperature change dλ / dT is −0.010 nm in the relationship between the thickness of the substrate and the change dλ / dT of the reflection center wavelength of the grating with respect to the temperature. /
Since a substrate having a thickness adjusted in advance so as to be in the range of ° C to 0.010 nm / ° C is used, the temperature change amount (dλ / dT) of the reflection center wavelength of the grating can be made substantially close to zero. In addition, the temperature dependency can be substantially eliminated.

Further, according to the optical waveguide grating device of the present invention, the core layer is composed mainly of SiO ₂ -based glass, Ge, Ti, Zr, Al, B, P,
Since it is made of SiO ₂ -based glass containing at least one or more additional elements selected from the group consisting of F, it can be adjusted to an appropriate refractive index.

According to the optical waveguide grating device of the present invention, the grating formed on at least a part of the core layer is formed by irradiating ultraviolet light to change the refractive index of at least a part of the core layer. So
A reflectance of about 100% can be easily obtained.

According to the method of manufacturing an optical waveguide grating device according to the present invention, a clad layer for accommodating a core layer is formed on a substrate made of a material having a linear thermal expansion coefficient larger than that of a core layer. Therefore, when the temperature rises, there is a difference between the linear thermal expansion coefficients of the substrate and the core layer, and thus the respective thermal expansion amounts are different. Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 Shift, S
The temperature stability of the grating can be improved by offsetting the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the iO ₂ -based material.

Further, it is possible to reduce the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ optical waveguide due to the ambient temperature change without the power consumption due to the temperature control and the like. Stable filter characteristics can be obtained. As a result, a significant cost reduction can be expected as compared with a structure in which temperature control is performed using a conventional Peltier element or the like. Also, compared to the conventional structure in which a metal plate having a higher linear thermal expansion coefficient than the substrate is bonded to the lower surface of the substrate,
Since the core layer and the cladding layer are formed directly on the substrate, the adhesion is excellent and the stress is transmitted uniformly, so that the temperature change of the reflection center wavelength can be effectively compensated.

According to the method of manufacturing the optical waveguide grating device according to the present invention, since the upper layer made of a material having a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the core layer is formed on the cladding layer, Occurs,
Since there is a difference in the coefficient of linear thermal expansion between the upper layer and the core layer, the respective layers have different amounts of thermal expansion. Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 By shifting the temperature, the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ -based material can be offset each other to improve the temperature stability. Further, since the upper layer plays a role of a protective film of the optical waveguide grating device, a highly reliable optical waveguide grating device can be obtained.

According to the method of manufacturing the optical waveguide grating device according to the present invention, the core layer and the cladding layer are formed on a substrate made of a material having a linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the core layer. , On the cladding layer,
Since the upper layer made of a material having a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the core layer is formed, if a temperature change occurs, the substrate and the core layer, and the respective lines of the core layer and the upper layer, Since there is a difference in thermal expansion coefficients, the respective thermal expansion amounts are different. Stress occurs due to the difference in thermal expansion amount, by reducing the period of the grating Λ is bent core layer comprising a grating as bimetal, the reflection center wavelength lambda _c of the grating to the short wavelength side in accordance with the number 1 By shifting the temperature, the temperature change of the reflection center wavelength of the grating due to the temperature change of the refractive index of the SiO ₂ -based material can be offset each other to improve the temperature stability.

In the above case, the substrate was made of SiO ₂ of the core layer.
Since a material having a higher linear thermal expansion coefficient than that of the base glass is used, and a material having a lower linear thermal expansion coefficient than the SiO ₂ glass of the core layer is used for the upper layer, the material from both below and above the core layer is used. The stress allows the grating of the core layer to be smoothly bent.

Further, according to the method of manufacturing an optical waveguide grating device according to the present invention, before forming a cladding layer on a substrate, a selection is made between a linear thermal expansion coefficient of the substrate and a linear thermal expansion coefficient of the core layer. Since at least one intermediate layer made of a material having a given linear thermal expansion coefficient is formed between the substrate and the cladding layer, the difference in linear thermal expansion coefficient between the SiO ₂ glass of the core layer and the substrate is extremely large. It is possible to prevent the occurrence of cracks due to internal strain of the optical waveguide that may occur when the optical waveguide is large. In this case, the intermediate layer plays a role of a buffer for relieving a large stress applied to the core layer and the clad layer, thereby preventing damage to the entire optical waveguide due to distortion. Further, by providing the intermediate layer, mutual ion diffusion between the substrate and the cladding layer can be prevented.

Further, according to the method of manufacturing the optical waveguide grating device according to the present invention, the change amount dλ / d of the thickness of the substrate and the reflection center wavelength of the grating with respect to the temperature is obtained.
In relation to T, the temperature variation dλ / dT is −0.010 n
Since a substrate having a thickness adjusted in advance so as to be in the range of m / ° C. to 0.010 nm / ° C. is used, the temperature change amount (dλ / dT) of the reflection center wavelength of the grating should be substantially close to zero. And the temperature dependency can be substantially eliminated.

[Brief description of the drawings]

1A is a cross-sectional view taken along a waveguide of an optical waveguide grating filter according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of the optical waveguide grating filter of FIG. FIG. 9 is a cross-sectional view showing a case where the substrate is bent due to a difference in linear thermal expansion coefficient between the substrate and the core layer when there is.

FIG. 2 is a diagram showing each component of the optical waveguide grating filter of FIG. 1;

3A and 3B are diagrams showing a manufacturing process of the optical waveguide grating filter of FIG. 1; FIG. 3A shows an under cladding layer 4 formed on a substrate 21 by a plasma CVD method;
It is sectional drawing which shows the core layer 5, (b) is sectional drawing which shows the Cr film | membrane 25 (metal film) for masks formed on the core layer 5 by the sputtering method, (c) is on the Cr film 25. FIG. 3D is a cross-sectional view showing the formed resist layer 26, and FIG. 4D shows the resist layer 2 patterned by photolithography.
6 (e) is a cross-sectional view showing a Cr film 25 patterned by a dry (wet) etching process, and (f) is a cross-sectional view showing a patterned Cr film 2;
FIG. 5G is a cross-sectional view showing the core layer 5 processed into a convex shape by RIE (Reactive Ion Etching) using the mask 5 as a mask, and FIG.
FIG. 4 is a cross-sectional view showing the core layer 5 from which the Cr film 25 has been removed by wet etching, and FIG. 4H shows an over clad layer 6 formed by a TEOS-O ₃ CVD method on the core layer 5 processed into a convex shape. It is sectional drawing.

FIG. 4 is a plasma CVD apparatus 3 used in the first embodiment.
FIG.

FIG. 5 is a sectional view taken along a waveguide of an optical waveguide grating device according to a second embodiment of the present invention.

FIG. 6 shows a substrate 21 used in a third embodiment of the present invention.
The type and thickness of the substrate material is a graph showing the relationship between the temperature change amount of the reflection center wavelength λ _c (dλ / dT).

FIG. 7 shows a substrate 21 used in a third embodiment of the present invention.
The type and thickness of the substrate material is a graph showing the relationship between the temperature change amount of the reflection center wavelength λ _c (dλ / dT).

FIG. 8 is a sectional view taken along a waveguide of an optical waveguide grating device according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing an example of a band-pass filter using a conventional optical waveguide grating filter.

FIG. 10 is a diagram illustrating an example of a multiplexing / demultiplexing circuit using the optical waveguide grating filter of FIG. 9;

11A is a cross-sectional view taken along a waveguide of a multiplexing / demultiplexing circuit using the optical waveguide grating filter of FIG. 10, and FIG. 11B is a cross-sectional view cut perpendicular to the waveguide. is there.

12 is a diagram illustrating a grating in the multiplexing / demultiplexing circuit of FIG. 11;
Reflection center wavelength λ _c5 is a graph showing a change in temperature of FIG.

[Explanation of symbols]

1 optical waveguide grating device, 2 gratings, 3 substrates, 4 under cladding layers, 5 core layers,
6 over cladding layer, 7 cladding layer, 10 optical waveguide grating filter, 11, 12 optical waveguide, 1
3, 14 grating, 15 3dB coupler, 16
Fiber connector, 20 multiplexing / demultiplexing circuit, 21 Al substrate, 22 upper layer, 23 intermediate layer, 25 Cr film, 26
Resist film, 30 plasma CVD apparatus, 31 upper shower electrode, 32 high frequency electrode, 33 matching circuit, 34 high frequency power supply, 35 to 37 material container, 38
Oxygen gas supply port, 39 to 42 mass flow controller, 43 reaction vessel, 44 substrate, 45 plasma,
46 Evacuation system.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshishin Kiyoshi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Masakazu Takabayashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo No. Mitsubishi Electric Co., Ltd. (72) Gen Takeya, 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Sadayuki Matsumoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Rishi Electric Co., Ltd. F term (reference) 2H047 KA04 KA11 KB04 LA02 LA18 PA11 PA30 QA04 TA00

Claims (12)

[Claims] 1. An optical waveguide grating device comprising: a substrate, a clad layer for accommodating a core layer formed thereon, and a grating formed on at least a part of the core layer. An optical waveguide grating device comprising a material having a linear thermal expansion coefficient larger than a linear thermal expansion coefficient. 2. An optical waveguide grating device comprising a clad layer for accommodating a core layer formed on a substrate, and a grating formed on at least a part of the core layer, wherein the core is formed on the clad layer. An optical waveguide grating device, wherein an upper layer made of a material having a linear thermal expansion coefficient smaller than that of the layer is formed. 3. An optical waveguide grating device comprising: a substrate, a clad layer for accommodating a core layer formed thereon, and a grating formed on at least a part of the core layer. An upper layer made of a material having a coefficient of linear thermal expansion larger than the coefficient of linear thermal expansion of the core layer is formed on the cladding layer. Optical waveguide grating device. 4. The method according to claim 1, wherein the at least one intermediate layer made of a material having a coefficient of linear thermal expansion selected between a coefficient of linear thermal expansion of the substrate and a coefficient of linear thermal expansion of the core layer is formed between the substrate and the cladding layer. 4. The optical waveguide grating device according to claim 1, further comprising: 5. The substrate according to claim 1, wherein the thickness of the substrate and the change in the reflection center wavelength of the grating with respect to temperature, dλ /
In relation to dT, the temperature change dλ / dT is −
The optical waveguide grating device according to any one of claims 1 to 4, wherein the optical waveguide grating device has a thickness previously adjusted to be in a range of 0.010 nm / ° C to 0.010 nm / ° C. 6. The SiO ₂ -based glass comprises a SiO ₂ -based glass as a main component and at least one additional element selected from the group consisting of Ge, Ti, Zr, Al, B, P and F. The optical waveguide grating device according to any one of claims 1 to 5, wherein the optical waveguide grating device is made of a _two- system glass. 7. The grating provided on at least a part of the core layer, wherein the grating is formed by irradiating ultraviolet light to change a refractive index of at least a part of the core layer. The optical waveguide grating device according to any one of claims 1 to 6. 8. A method of manufacturing an optical waveguide grating device, comprising: forming a clad layer for accommodating a core layer on a substrate, and forming a grating on at least a part of the core layer, wherein the substrate comprises: A method of manufacturing an optical waveguide grating device, comprising a material having a linear thermal expansion coefficient larger than a linear thermal expansion coefficient of the core layer. 9. A method for manufacturing an optical waveguide grating device, comprising: forming a clad layer for accommodating a core layer on a substrate, and forming a grating on at least a part of the core layer. And forming an upper layer made of a material having a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the core layer. 10. A method for manufacturing an optical waveguide grating device, comprising: forming a clad layer for accommodating a core layer on a substrate, and forming a grating on at least a part of the core layer, wherein the substrate comprises: An upper layer made of a material having a linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the core layer, and an upper layer made of a material having a linear thermal expansion coefficient smaller than the linear thermal expansion coefficient of the core layer is formed on the cladding layer. A method for manufacturing an optical waveguide grating device, further comprising a step. 11. Before forming the cladding layer on the substrate, at least a material having a linear thermal expansion coefficient selected between a linear thermal expansion coefficient of the substrate and a linear thermal expansion coefficient of the core layer. The method according to claim 8, further comprising forming one intermediate layer between the substrate and the cladding layer. 12. The substrate has a thickness d of the substrate and a change amount dλ of a reflection center wavelength of the grating with respect to a temperature.
/ DT, wherein the temperature change amount dλ / dT has a thickness adjusted in advance so as to fall within a range of -0.010 nm / ° C to 0.010 nm / ° C. The method for manufacturing the optical waveguide grating device according to any one of the above items.