JP3225878B2 - Polymer waveguide and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer waveguide formed using a polymer material and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, research and development of polymer waveguides have become active. This is because it is considered promising for realizing a low-cost optical device. FIG. 9 shows a conventional example of a polymer waveguide. The polymer waveguide shown in FIG.
Cladding layers 11-1 and 11-2 made of a polymer material are formed on the surface of a substrate (such as Si glass) 10, and a polymer material having a higher refractive index is provided in the cladding layers 11-1 and 11-2. And has a structure in which a core layer 12 is embedded. Core layer 12 and cladding layers 11-1, 11
-2 polymer materials include PMMA (polymethyl methacrylate), polystyrene, polyimide, polyguide, epoxy resin, polysiloxane, and the like.

FIGS. 10A, 10B, and 10C show a conventional example of a method for manufacturing a polymer waveguide. A photosensitive polymer layer 15 whose refractive index is lowered by ultraviolet irradiation is formed on the surface of the substrate 10, and a mask 16 is formed on the surface of the polymer layer 15.
Are arranged, and ultraviolet rays 17 are irradiated from above the mask 16 (FIG. 10A). In the polymer layer 15, the exposed portion 15a irradiated with the ultraviolet light 17 transmitted through the mask 16 has a low refractive index, and the exposed portion 15b not irradiated with the ultraviolet light 17 in the mask 16 does not change its refractive index. (FIG. 10B). By using the exposed portion 15b as a light waveguide layer (that is, the core layer 12) and covering the core layer 12 with the clad layer 11, a polymer waveguide is formed (FIG. 10C).

FIGS. 11A to 11D show another conventional method for manufacturing a polymer waveguide. A core polymer waveguide layer 19 through which light propagates is formed on the surface of the substrate 10, and a mask 16 is placed on the surface to irradiate ultraviolet rays 17 (FIG. 1).
1 (a)). The exposed portion 19a irradiated with the ultraviolet light 17 transmitted through the mask 16 is removed by etching, and the exposed portion 19b not irradiated with the ultraviolet light 17 by the mask 16 remains as the core layer 12 having a substantially rectangular cross-sectional shape (FIG. 11).
(B), (c)). A core layer 12 having a substantially rectangular cross-sectional shape is formed of a clad layer 11 made of a polymer having a refractive index lower than that of the core layer 12.
To form a polymer waveguide (FIG. 11).
(D)).

FIGS. 12A to 12D show still another conventional method of manufacturing a polymer waveguide. A core polymer waveguide layer 19 through which light propagates is formed on the surface of the substrate 10, and a mask pattern 20 is formed on the surface. As the material of the mask pattern 20, a resist material, an oxide film material or a metal material is used. Next, ultraviolet rays 17 are irradiated from above the mask pattern 20 (FIG. 12A). In the core polymer waveguide layer 19, a portion where the mask pattern 20 is not formed is irradiated with the ultraviolet light 17, and a portion where the mask pattern 20 is formed is not irradiated with the ultraviolet light 17. The exposed portion of the core polymer waveguide layer 19 irradiated with the ultraviolet rays 17 is removed by etching (FIG. 12B). The mask pattern 20 remaining on the surface of the exposed portion 19b of the core polymer waveguide layer 19 is peeled off, and the surfaces of the core layer 12 and the substrate 10 are clad with a cladding layer 11 made of a polymer having a refractive index lower than that of the core layer 12. To form a polymer waveguide (FIG. 12C).

[0006]

However, the above-mentioned conventional polymer waveguide has the following problems. (1) The core layer 12 and the cladding layers 11-1, shown in FIG.
The interfaces 14-1, 14-2, and 14-3 with 11-2 became non-uniform, and the scattering loss of light due to this was not negligible. Such irregularities in the interface are inevitable when the core layer 12 is etched or covered with the cladding layers 11-1 and 11-2. (2) Further, as shown in FIG. 9, there is a problem that the flatness of the upper surface of the cladding layer 11-2 is poor. In particular, FIG.
It can be seen that it is difficult to flatten the upper surface of the cladding layer 11-2 as long as the method of forming the core layer 12 having a substantially rectangular cross-sectional shape and then covering the upper surface with the cladding layer 11 is used. Was. As shown in FIG. 13, when the flatness is poor, it is difficult to provide the thin film heater 21 on the surface of the cladding layer 11-2. Because
The thin-film heater 21 firstly includes the polymer clad layer 11-
2 is formed by depositing a metal film on the surface of the metal film 2 and then forming a resist pattern on the surface of the metal film and performing an etching process using the resist pattern as a mask. If the top surface is not flat, it is difficult to deposit a metal film, and it is also difficult to apply a resist film to a uniform thickness. As a result, it becomes difficult to form a fine pattern of the thin film heater 21 by etching. FIG. 13A is a plan view when a thin film heater 21 is provided on the surface of a conventional polymer waveguide, and FIG. 13B is a cross-sectional view taken along line AA of FIG. Here, 22 is a power source, 23 is a switch, and 24-26.
Is a signal light, and the other reference numerals are common to FIGS. (3) Since the number of manufacturing steps is large, it is difficult to reduce the cost of the polymer waveguide. (4) A high performance single mode transmission polymer waveguide type optical component requiring high dimensional accuracy cannot be realized. For example, an N-channel wavelength division multiplexing transmission duplexer, 1 ×
It is difficult to realize an optical component such as an M (or N × M) optical star coupler with high performance (low loss, control of center wavelength, high isolation characteristics, low distribution deviation characteristics, etc.). (5) It is difficult to form a so-called flexible polymer waveguide type optical component having a very small thickness (100 μm or less) with high performance and high dimensional accuracy. The reason is that it is difficult to maintain high dimensional accuracy with a thin substrate due to a processing process such as etching.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polymer waveguide capable of reducing the loss, flattening the upper surface of the cladding layer, increasing the dimensional accuracy, reducing the thickness of the substrate, and simplifying the manufacturing process, and manufacturing the same. It is to provide a method.

[0008]

To achieve the above object, according to an aspect of the present invention, as a first aspect, a substrate, a buffer layer of refractive index n _b, which is formed on a surface of the substrate, PMMA
The DMAPN propagation capable refractive index n _w of dispersed the light signal (where, n _w> n _b) a core layer, and the light energy refractive index n _i of DMAPN in PMMA has been evaporated by irradiation (however, PMM formed flat on the surface of the buffer layer with a side cladding layer of n _i <n _w )
A layer and refractive index n _c formed on the surface of the PMMA layer
(Where n _c <n _w ) An upper clad layer is provided.

[0009]

Further, according to the present invention, as a second feature, a buffer layer is formed on the surface of the substrate, a PMMA layer in which DMAPN is dispersed is formed on the surface of the buffer layer, and the light transmitting portion and the light shielding portion are patterned. PM with the photomask
Covering the MA layer, irradiating the PMMA layer with light energy, and evaporating DMAPN of the PMMA layer in the region irradiated with the light energy through the light transmitting portion, thereby lowering the refractive index of the region. Forming a side cladding layer and forming a core layer while maintaining the refractive index of the remaining region corresponding to the light shielding portion; and forming an upper cladding layer on the surface of the PMMA layer. A manufacturing method is provided.

[0011]

[0012]

Embodiments of the present invention will be described below with reference to the drawings.
This will be described with reference to FIG. FIG. 1 shows a polymer waveguide according to the present invention.
1 shows a first embodiment of the present invention. Refractive index on the surface of substrate 101
n_bPMMA layer (hereinafter referred to as buffer layer) 102
(First layer) is formed with a thickness of several μm. This battery
DMAPN dispersed refractive index n on the surface of the
_w(However, n_w> N_b) PMMA layer (hereinafter referred to as core layer)
103) is provided. On the outer periphery of the core layer 103
Is CO_TwoDMAPN evaporates due to laser beam irradiation and yields.
Folding ratio n_i(However, n_i<N_wPMMA layer changed to)
(It functions as a ground layer on the side.
A cladding layer 104 is provided (the core layer 103 and the
And the side cladding layer 104 constitutes the second layer).
So as to cover the layer 103 and the side cladding layer 104.
Refractive index n_c(However, n _c<N_w) PMMA layer (hereinafter, referred to as
105 (third layer) is formed.
I have. The material of the substrate 101 may be glass, semiconductor, ferroelectric
A body, a magnetic body, a plastic, or the like can be used.

As the core layer 103, for example, DMAPN
Is 10% dispersed, the wavelength 0.6
The refractive index at 328 μm is 1.513. Also,
The side cladding layer 104 has a refractive index of 1.513 to 1.486 at a wavelength of 0.6328 μm depending on the irradiation energy (depending on irradiation time and irradiation power) of the CO ₂ laser beam.
Can be changed up to 5. That is, the amount of DMAPN evaporated can be adjusted by the irradiation energy, and the refractive index can be controlled. Buffer layer 102 and upper cladding layer 1
05 has a refractive index of about 1.486 at a wavelength of 0.6328 μm.
5

In order to realize a single-mode transmission waveguide in the polymer waveguide of FIG.
Has a thickness and width of several μm, and the relative refractive index Δ of the core layer 103, the side cladding layer 104, and the upper cladding layer 105 (or the buffer layer 102) is 0.1 μm. Several% to 1. It is selected from a range of several percent. To realize a multimode transmission waveguide, the thickness and width of the core layer 103 are several μm.
m or more (a range close to 10 μm to several tens of μm),
The relative refractive index Δ is also set to a value larger than a value near 1%.

The relative refractive index Δ between the core layer 103 and the side cladding layer 104 can be changed up to about 1.75% by irradiating the side cladding layer 104 with CO ₂ laser light. If the relative refractive index Δ between the core layer 103 and the upper cladding layer 105 (or the buffer layer 102) is also adjusted to the relative refractive index Δ between the core layer 103 and the side cladding layer 104, the upper cladding layer 105 and the buffer By changing the polymer material of the layer 102 accordingly, a desired relative refractive index Δ can be easily achieved. For example, as a combination of PMMA-compatible polymer materials, 4-alkoxy-4'-alkyl-sulfone
-stilbend PMMA side-chain or PMMA
A material in which a polymer material having a higher refractive index than MMA is dispersed, and a polymer material other than PMMA, for example, an alicyclic PMMA material can be used.

In order to realize a value larger than the relative refractive index Δ, a polymer material obtained by adding F to PMMA may be used for the upper cladding layer 105 and the buffer layer 102. Further, when it is desired to lower the refractive index of the core layer 103 a little, as described later, the core layer 103 and the side cladding layer 104 are irradiated with ultraviolet rays (wavelength 365 μm band). Can be lowered. For example, an ultraviolet ray of 75 mJ /
irradiated at an intensity of cm ^2, then, by heating at a temperature range of 50 ° C. to 80 ° C. for about 60 minutes, the refractive index of the core layer 103 is changed to 1.513 to 1.4964, and a side cladding layer 104 Can be changed from 1.4964 to 1.4865 by CO ₂ laser beam irradiation. Conversely, when the refractive index of the core layer 103 is increased, the dispersion concentration of DMAPN may be increased. For example, when the dispersion concentration of DMAPN is 30
%, The refractive index can be increased to about 1.53. As described above, by appropriately selecting the type of the polymer material and irradiating and irradiating the ultraviolet rays, the relative refractive index Δ can be controlled in a wide range.

FIG. 2 shows a second embodiment of the polymer waveguide according to the present invention. In FIG. 2, the buffer layer 102
As the material of the upper cladding layer 105, oxide films 102a and 105a are used instead of the polymer material. The oxide film, SiO _2, or SiO ₂ P (phosphorus), B
(Boron), Ti (titanium), Ge (germanium),
What contains at least one kind of additive for controlling the refractive index such as Al (aluminum) can be used.

FIG. 3 shows a manufacturing process in the method for manufacturing the polymer waveguide of FIG. First, as shown in (a), a buffer layer 1 is formed on the surface of a substrate 101 by a PMMA layer.
02 is formed. The method of forming the buffer layer 102 is as follows.
A solution obtained by dissolving PMMA in an organic solvent is applied to the surface of the substrate 101 by a spin coating method, and then the organic solvent is evaporated through a drying step of pre-baking and post-baking to solidify PMMA.

Next, as shown in FIG. 3B, a PMMA layer (core layer 103) in which DMAPN is dispersed is formed on the surface of the buffer layer 102. The core layer 103 is also formed by dissolving PMMA in which DMAPN is dispersed in an organic solvent, and performing the steps of spin coating, prebaking, and postbaking. Thereafter, as shown in FIG. 3 (c), placing the CO ₂ laser mask 106 on the surface of the core layer 103, does not transmit the CO ₂ laser beam 107 from above the CO ₂ laser mask 106 pattern portions 106a (Light shield)
106b through which the CO ₂ laser beam 107 passes
(Light transmitting portion) is patterned. DMAP below the pattern portion 106b through which the CO ₂ laser beam 107 has passed
In the PMMA layer in which N is dispersed, DMAPN evaporates according to the amount of energy of the CO ₂ laser beam 107, and the refractive index can be changed according to the amount of evaporation. On the other hand, CO
₍₂ ) The pattern portion 106a through which the laser beam 107 has not passed
The DMPN dispersed PMMA layer below does not cause a refractive index change.

As shown in then (d), removing the CO ₂ laser mask 106, PMMA layer CO ₂ laser light 107 is dispersed in DMAPN youngest irradiation (core layer 10
3) and a PMMA layer (side cladding layer 104) irradiated with the CO ₂ laser beam 107 is obtained. Side cladding layer 10
The content of DMAPN in 4 depends on the irradiation energy of the CO ₂ laser beam 107. Finally, as shown in (e), the surfaces of the core layer 103 and the side cladding layer 104 are flat, so that the PMM is
The upper cladding layer 105 is formed by A. Thus, a polymer waveguide having the configuration shown in FIG. 1 can be obtained. Upper clad layer 1 of polymer waveguide thus obtained
05 has an extremely flat surface.

Next, with reference to FIG. 3, a method of manufacturing a polymer waveguide having a core layer whose refractive index is lowered by irradiating the PMMA layer in which DMAPN is dispersed with ultraviolet light having a wavelength of 365 μm band will be described. In this manufacturing method, PMMA in which DMAPN is dispersed between (b) and (c) of FIG.
A step of irradiating the surface of the layer (core layer 103) with ultraviolet light having a wavelength band of 365 μm is inserted. After the ultraviolet irradiation, the surface is placed in a heating furnace and baked (at 50 ° C. to 80 ° C. for 1 hour). Thereafter, the steps shown in FIGS. 3C to 3E are sequentially performed.

FIG. 4 shows the result of changing the refractive index by irradiating the CO ₂ laser beam to the DMAPN-dispersed core layer 103 of FIG. 3C. CO ₂
An example is shown in which the refractive index of the core layer 103 changes as the irradiation time of the laser light increases (that is, the irradiation energy increases). FIG. 5 shows that the core layer 103 in which DMAPN is dispersed is irradiated with ultraviolet light, and then the core layer 103 is dispersed.
₂ shows how the refractive index of the core layer 103 changes by irradiating the surface of the substrate with a CO ₂ laser beam. However, the amount of ultraviolet light (wavelength 365 μm band) is 75 mJ / c.
m ² , and baking is performed at 50 ° C. to 80 ° C. for about 60 minutes after irradiation with ultraviolet rays.

Next, a method of manufacturing the polymer waveguide of FIG. 2 will be described with reference to FIG. The buffer layer 102 of FIG.
The oxide film 102a is formed instead of the formation of the oxide film 102a. The oxide film 102a is formed by CVD (chemical vapor deposit).
ion), an electron beam evaporation method, a sputtering method, a sol-gel method and the like. After that, it is manufactured according to the steps (b) to (d) of FIG.
Finally, an oxide film 105a is formed instead of forming the upper cladding layer 105 of FIG. However, in order to form the final oxide film 105a, it is necessary to form the oxide film 105a at a film formation temperature of 80 ° C. or less, and a low-temperature CVD method, a low-temperature sputtering method, or a spin coating method of a SiO ₂ solution dissolved in alcohol. And so on.

In the structure shown in FIG. 2, a polymer material can be used instead of the oxide film. Also, PMMA
As a material to be dispersed therein, besides DMAPN, dyepolym
er, 4-dialkylamino-4'-nitro-stilbene and the like can be used. FIG. 6 shows a third embodiment of the polymer waveguide according to the present invention. In FIG. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.
On the surface of the substrate 101, a buffer layer 102 having a refractive index n _b
Is formed to a thickness of 5 μm to several tens μm. A side cladding layer 109 having a refractive index n _c1 (where n _c1 <n _w ) is formed on the upper surface of the buffer layer 102, and a core layer having a refractive index n _w (where n _w > n _b ) is provided at a predetermined position. 110 are formed. The core layer 110 and the side cladding layer 109
Is provided with an upper cladding layer 111 having a refractive index of n _c2 (where n _c2 <n _w ), and a UV cut layer 112 is formed on the upper surface of the upper cladding layer 111. As described later, the side cladding layer 109 and the core layer 110 can be formed by providing a photobleaching material layer on the surface of the buffer layer 102 and selectively irradiating the photobleaching material layer with ultraviolet rays. .

Glass, polymer, or the like can be used as the material of the buffer layer 102. That is, it is possible to use SiO ₂ , SiO ₂ containing at least one or more kinds of refractive index controlling additives such as P, B, Ti, Ge, Al, and F, and a polymer such as PMMA. The photobleaching material for forming the side cladding layer 109 and the core layer 110 includes, for example, DMPAN @ α- (4-
dimethlaminophenyl) -N-phenylnitron｝ can be used. The photochemical rearrangement of this polymer material has a wavelength of 380
Photobleaching at 270 nm results in a new absorption of the okinazylidene photoproduct at a wavelength of 270 nm. The side cladding layer 109 irradiated with ultraviolet rays (its refractive index is n _c1 )
When irradiating ultraviolet rays having a wavelength of 380 nm at 100 mJ / cm ² , the refractive index decreases.

Here, the side cladding layer 109 and the core layer 110 are made of PMMA in which DMAPN is dispersed by 10%.
The side cladding layer 109 is irradiated with ultraviolet rays having a wavelength of 365 nm at about 80 mJ / cm ² , and a wavelength of 0.6328.
The refractive index at μm was kept at 1.513. In addition, the core layer 1
The thickness and width of 10 are selected from a range of several μm to 10 μm when a single-mode transmission waveguide is used, and are selected from a range of 10 μm to several tens μm when a multi-mode transmission waveguide is used. Note that the thickness of the side cladding layer 109 is equal to the thickness of the core layer 110.

The refractive index n _c2 of the upper cladding layer 111 is substantially equal to the value of the buffer layer 102. Therefore, the same material as the buffer layer 102 can be used for the material of the upper cladding layer 111. The thickness of the upper cladding layer 111 is 1
The range of 0 μm to several tens μm is preferable. UV cut layer 11
2 is a glass to which Ce ³⁺ is added (for example, CeO ₂
Added to soda-lime glass), Ti ⁴⁺ , V ⁵⁺ , C
Glass to which r ⁶⁺ , U ⁶⁺ , Pb ^2+, or the like is added can be used. Or benzophenone, cinnamic acid, P
Ultraviolet absorbers such as ABA (P-aminobenzoic acid), salicylic acid, and dibenzoylmethane can be used. The thickness of the UV cut layer 112 is preferably thicker, and can be selected from a range of several μm to 100 μm.

As described above, the reason why the UV cut layer 112 is provided is that indoor and outdoor ultraviolet rays using a polymer waveguide are transmitted through the upper cladding layer 111 and are irradiated on the core layer 110.
This is to prevent the refractive index of the core layer 110 from gradually decreasing. By taking this measure, it is possible to maintain the relative refractive index constant for a long time, and to provide an optical signal processing circuit such as an optical branching circuit, an optical star coupler, or an optical filter using such a polymer waveguide with stable characteristics for a long time. Can be maintained.

FIG. 7 shows a fourth embodiment of the polymer waveguide according to the present invention. In FIG. 7, the same reference numerals are used for the same components as those in FIG. 6, and the duplicate description will be omitted.
7 differs from FIG. 6 in that a cladding layer 113 containing a UV-cut material is provided instead of the upper cladding layer 111 and the UV-cut layer 112 in FIG. As described above, for the cladding layer 113 containing the UV cut material, a polymer material can be used as the glass material containing the UV cut material.

In the present embodiment, the reason why the cladding layer 113 containing the UV-cutting material is provided is that ultraviolet rays from inside and outside the room using the polymer waveguide are transmitted through the cladding layer 113 and irradiated on the core layer 110, This is to prevent the refractive index of 110 from gradually decreasing. FIG. 8 shows a manufacturing process of the polymer waveguide of FIG. First, as shown in (a), a buffer layer 102 is formed on a surface of a substrate 101 by plasma C.
It is formed by a VD method, a sputtering method, an electron beam evaporation method, a spin coating method, or the like. Then
As shown in (b), a polymer layer 114 for photobleaching is formed on the surface of the buffer layer 102 by a spin coating method. The polymer layer 114 is formed by applying a photobleaching polymer dissolved in an organic solvent to the surface of the buffer layer 102 by a spin coating method.
It can be formed by evaporating the organic material by baking and solidifying the polymer layer.

Next, as shown in FIG. 8C, a mask 115 is provided on the surface of the polymer layer 114 for photobleaching. The mask 115 has a light transmitting portion 115a that transmits ultraviolet light and a light blocking portion 115b that does not transmit ultraviolet light. UV light 11 having a wavelength of 360 nm from above the mask 115.
Irradiate 6. By this ultraviolet irradiation, as shown in (d), the photobleaching polymer layer 114 has a photobleaching portion irradiated with ultraviolet light becomes the core layer 110 and a non-photobleaching portion not irradiated with ultraviolet light has side surfaces. It becomes the cladding layer 109. The refractive index of the core layer 110 is lower than that of the side cladding layer 109.

Finally, as shown in FIG. 8E, an upper clad layer 111 containing a UV cut material is provided on the upper surfaces of the side clad layer 109 and the core layer 110. The upper cladding layer 111 is formed by the same method as the method of forming the buffer layer 102. Thus, the polymer waveguide having the configuration shown in FIG. 6 is completed. The above is the method of manufacturing the polymer waveguide of FIG. 7. In the case of the polymer waveguide of FIG. 6, instead of the process of FIG. 8E, an upper portion is formed on the upper surface of the photo-bleaching portion and the non-photo-bleaching portion. The steps of providing the cladding layer 111 and providing the UV cut layer 112 may be performed.

In the structure shown in FIGS. 6 and 7, the substrate 1
01 may be provided with a UV cut layer or a UV cut material, and the buffer layer 102 may be formed with a UV cut layer or a UV cut material. With this configuration, it is possible to prevent ultraviolet light from inside and outside the room using the polymer waveguide from reaching the core layer 110 through the substrate 101 and the buffer layer 102, and from gradually lowering the refractive index of the core layer 110.

[0034]

As described above, according to the polymer waveguide of the present invention, the PMMA layer in which DMAPN is dispersed is provided flat on the buffer layer, and the PMMA layer is selectively irradiated with light energy to form the core layer. and since to form the side cladding layer, it is possible to form a Tan Taira cladding layer, thereby can realize an optical circuit of a high function, further, easily optical circuit be thinner the thickness of the substrate Can be created. As a result, it is possible to suppress a change in the dimensions of the core layer and an increase in light loss due to the irregular structure of the interface between the core and the cladding layer.

Further, according to the method for manufacturing a polymer waveguide of the present invention, a PMMA layer in which DMAPN is dispersed is formed on the surface of a buffer layer, and the PMMA layer is covered with a mask having a light transmitting portion and a light shielding portion. since so as to form a core layer and a side cladding layer by a change in refractive index due to the presence or absence of transmission of light energy irradiated towards the layer, it is possible to form a flat cladding layer by straightforward single process,
As a result, a high-performance optical circuit can be realized, and an optical circuit can be easily formed even if the substrate is thin. Therefore,
It is possible to suppress an increase in light loss due to a dimensional variation of the core layer and an irregular structure at the interface between the core and the cladding layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a polymer waveguide according to the present invention.

FIG. 2 is a cross-sectional view showing a second embodiment of the polymer waveguide according to the present invention.

FIG. 3 is an explanatory view showing a manufacturing process in the method for manufacturing the polymer waveguide of FIG. 1;

FIG. 4 is a refractive index characteristic diagram showing a result of changing a refractive index by irradiating a core layer shown in FIG. 3 with a CO ₂ laser beam.

FIG. 5 is a refractive index characteristic diagram showing a result obtained by irradiating the core layer shown in FIG. 3 with ultraviolet rays and then irradiating the core layer with a CO ₂ laser beam to change the refractive index.

FIG. 6 is a cross-sectional view showing a third embodiment of the polymer waveguide according to the present invention.

FIG. 7 is a sectional view showing a fourth embodiment of the polymer waveguide according to the present invention.

FIG. 8 is an explanatory view showing a manufacturing process of the polymer waveguide of FIG. 7;

FIG. 9 is a sectional view showing a conventional example of a polymer waveguide.

FIG. 10 is a process chart showing a conventional example of a method for manufacturing a polymer waveguide.

FIG. 11 is a process chart showing another conventional method for manufacturing a polymer waveguide.

FIG. 12 is a process chart showing still another conventional method for manufacturing a polymer waveguide.

13A and 13B show a configuration example of a conventional polymer waveguide, and FIG.
Is a plan view of a polymer waveguide provided with a thin film heater on the upper surface,
(B) is a sectional view taken along line AA of (a).

[Explanation of symbols]

101 substrate 102 buffer layer 103, 110 core layers 104 and 109 side cladding layer 105 and 111 upper cladding layer 102a, 105a oxide film 106 CO ₂ laser mask 107 CO ₂ laser beam 112 UV cut layer 113 cladding layer 114 for photobleaching Polymer layer 115 Mask 115a Light transmitting part 115b Light shielding part 116 UV

Continuation of the front page (56) References JP-A-8-15537 (JP, A) JP-A-10-48443 (JP, A) JP-A-3-154006 (JP, A) JP-A-62-69207 (JP, A) JP-A-52-138146 (JP, A) JP-A-3-288103 (JP, A) JP-A-9-178901 (JP, A) JP-A-2-113210 (JP, A) JP-A-10-16007 (JP, A) JP-A-6-18739 (JP, A) JP-A-56-8008 (JP, A) JP-A-1-134311 (JP, A) A) Applied Optics Vol. 34, no. 9 (1995) p. 1554− 1561 (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/12-6/14 G02F 1/29-7/00 JICST file (JOIS)

Claims (8)

(57) [Claims] 1. A substrate, a buffer layer having a refractive index of n _b formed on the surface of the substrate, and a refractive index n _w (where n _w > n) capable of propagating an optical signal by dispersing DMAPN in PMMA. the core layer of _b), and the refractive index n _i (where the DMAPN in PMMA has been evaporated by irradiation of light energy, formed flat on the surface of the buffer layer in a state having a side cladding layer of n _i <n _w) and PMMA layer, the refractive index n _c that is formed on the surface of the PMMA layer (provided that
n _c <Polymer waveguides, characterized in that it comprises an upper cladding layer of n _w). 2. The polymer waveguide according to claim 1, wherein said buffer layer is made of a polymer material or an inorganic material. 3. The core layer according to claim 1, wherein a dispersion ratio of DMAPN is 1
2. The polymer waveguide according to claim 1, wherein the ratio is 0%. 4. The polymer waveguide according to claim 1, wherein the upper cladding layer uses a polymer material or an inorganic material. 5. A buffer layer is formed on a surface of a substrate, a PMMA layer in which DMAPN is dispersed is formed on a surface of the buffer layer, and the PMMA layer is covered with a photomask in which a light transmitting part and a light shielding part are patterned. By irradiating the PMMA layer with light energy and evaporating DMAPN of the PMMA layer in the region irradiated with the light energy through the light transmitting portion, the refractive index of the region is reduced, and the side cladding layer is formed. A method of manufacturing a polymer waveguide, comprising: forming a core layer while maintaining a refractive index of a remaining region corresponding to the light shielding portion; and forming an upper clad layer on a surface of the PMMA layer. 6. The method according to claim 5 , wherein the irradiation of the light energy is performed using a CO ₂ laser beam. 7. The method of claim 5 , wherein the DMAPN is replaced by a dispersing polymer material having an evaporation temperature lower by at least 10 ° C. than PMMA. 8. The method according to claim 5 , wherein the PMMA layer is irradiated with ultraviolet rays before the photomask is installed.