JPH103013A - Polymer waveguide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer waveguide having a low loss and high heat resistance and a manufacturing method therefor. SOLUTION: A clad layer 13 made of a polymer material covers a core 12 made of a glass material having a low loss and high heat resistance, thereby, hydrogen of C-H group in the polymer structure of the core 12 is replaced by fluorine or deuterium. Thus, polymer material can be easily obtained. In order to acquire high heat resistance, the polymers in the core 12 are cross-liquid or aromatic groups are introduced in the polymer structure, thereby the polymer waveguide 10 having a low loss and high heat resistance can be easily realized without making a manufacturing process of the waveguide complex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer waveguide and a method for manufacturing the same.

[0002]

2. Description of the Related Art As an optical component, there is a polymer waveguide, which is used for an optical filter, an optical switch, a dispersion compensation circuit and the like.

FIG. 5 is a sectional view of a conventional polymer waveguide.

The polymer waveguide 1 has a core 3 having a rectangular cross section formed on a substrate 2, and the upper surface of the core 3 and the substrate 2 are covered with a cladding layer 4. The core 3 is made of a polymer material such as polymethyl methacrylate, polycarbonate, or polyimide. For the cladding layer 4, a polymer material such as polymethyl methacrylate, polycarbonate, or polyimide having a lower refractive index than the core 3 is used.

FIGS. 6A to 6F are process diagrams showing a method for manufacturing the polymer waveguide shown in FIG.

First, a core film 3a made of a polymer material such as polymethyl methacrylate, polycarbonate, or polyimide is formed on a substrate 2 made of SiO ₂ or Si by spin coating or the like (FIG. 6A).

A WSi film 5a is formed on the core film 3a by a sputtering method (FIG. 6B).

[0008] WSi mask pattern 5 covering a portion to be core 3 by photolithography and dry etching
Is formed (FIG. 6C).

The core 3 is formed by dry etching (FIG. 6D).

The WSi mask pattern 5 is removed by dry etching (FIG. 6E).

The polymer waveguide 1 is formed by covering the upper surfaces of the core 3 and the substrate 2 with a cladding layer 4 of a polymer material such as polymethyl methacrylate, polycarbonate, or polyimide having a lower refractive index than the core 3. (F)).

[0012]

By the way, in order to widen the application range of the polymer waveguide, low loss and high heat resistance are required. In a conventional polymer waveguide, as a method of reducing the loss, H in the C—H group in the core polymer structure is used.
It is common to replace (hydrogen) with fluorine F or deuterium D, and as a method of increasing the heat resistance, it is common to crosslink the polymer of the core or introduce an aromatic into the polymer structure. .

However, such a method makes it difficult to obtain a polymer material and complicates the manufacturing process of the waveguide, which is a problem in expanding the application range of the polymer waveguide.

An object of the present invention is to solve the above problems and to provide a polymer waveguide having low loss and high heat resistance and a method for manufacturing the same.

[0015]

Means for Solving the Problems] polymer waveguide of the present invention in order to achieve the above object, the optical waveguide core and cladding layer is formed on the substrate, SiO _X N _Y core
_HZ glass is used, and a polymer having a lower refractive index than the core is used for the cladding layer.

In addition to the above configuration, the polymer waveguide of the present invention comprises:
A heater may be provided near or inside the core.

In order to achieve the above object, a method of manufacturing a polymer waveguide according to the present invention comprises forming a core film made of SiO _X N _Y H _Z glass on a substrate, forming a WSi film on the core film, A WSi mask pattern is formed by performing photolithography and dry etching on the WSi film, and a core is formed by performing dry etching on the core film using the WSi mask pattern, and the core is formed of a polymer material having a lower refractive index than the core. The clad layer is formed so as to cover.

By covering the periphery of a core made of a glass material having low loss and high heat resistance with a cladding layer of a polymer material, hydrogen of a C--H group is replaced with fluorine or deuterium in the polymer structure of the core. Therefore, there is no difficulty in obtaining the polymer material. To achieve high heat resistance, low loss and high heat resistance polymer waveguides can be easily realized without complicating the waveguide manufacturing process by cross-linking the core polymer or introducing aromatics into the polymer structure. can do.

[0019]

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

FIG. 1 is a sectional view of a polymer waveguide according to the present invention.

The polymer waveguide 10 shown in FIG.
A core 12 having a rectangular cross-sectional shape is formed thereon, and the upper surfaces of the core 12 and the substrate 11 are covered with a cladding layer 13.

The core 12 is made of SiO _x N having a high refractive index.
A glass of _Y H _Z, the cladding layer 13 has a refractive index lower than the refractive index of the core 12, using a polymer material having a desired thickness.

FIG. 2 is a process chart showing a method for manufacturing the polymer waveguide shown in FIG.

On the substrate 11 made of SiO ₂ or Si, a glass core film 12a made of SiO _X N _Y H _Z having a high refractive index is formed by a plasma CVD method, a sputtering method, an ion beam method or the like (FIG. 2 ( a)).

A WSi film 14a is formed on the glass core film 12a by a sputtering method (FIG. 2B).

A WSi mask pattern 14 for covering a portion to be the core 12 is formed by photolithography and dry etching (FIG. 2C).

The core 12 is formed by dry etching (FIG. 2D).

The WSi mask pattern 14 is removed by dry etching (FIG. 2E). The core 12 and the upper surface of the substrate 11 are covered with a cladding layer 13 made of a polymer material such as polymethyl methacrylate, polycarbonate, or polyimide having a lower refractive index than the core 12, so that the polymer waveguide 10 has a low refractive index and high heat resistance. Is formed (FIG. 2F).

The polymer waveguide 10 is formed by covering the periphery of a core 12 made of a glass material having low loss and high heat resistance with a clad layer 13 made of a polymer material, so that a C—H group in the polymer structure of the core 12 is formed. Is replaced by fluorine or deuterium, so that it is not difficult to obtain a polymer material. In order to increase the heat resistance, a polymer waveguide having low loss and high heat resistance can be easily formed without complicating the manufacturing process of the waveguide by cross-linking the polymer of the core 12 or introducing aromatics into the polymer structure. Can be realized.

Next, description will be made with specific numerical values, but the present invention is not limited to these numerical values.

A polymer waveguide as shown in FIG. 1 was manufactured by the manufacturing method shown in FIG. The size is 4 μm so that the core 12 made of quartz glass becomes single mode.
m and a height of 3 μm. The thickness of the cladding layer 13 made of a polymer material was set to 10 μm. The length of the straight waveguide was set to 50 mm. Further, the relative refractive index difference between the core 12 and the cladding layer 13 was adjusted to be 2%.

As a comparative example, it was manufactured by the conventional method shown in FIG. The size was set to 4 μm in width and 3 μm in height so that the core 3 made of polymer was in a single mode. The thickness of the cladding layer 4 made of a polymer material was set to 10 μm.
The length of the straight waveguide was set to 50 mm. Further core 3
It was adjusted so that the relative refractive index difference between the cladding layer 4 and the cladding layer 4 was 2%.

The wavelength of 1.3 μm between the polymer waveguide of the present invention having a core made of silica-based glass thus obtained and the conventional polymer waveguide having a core made of polymer was obtained.
Table 1 shows the loss at m.

[0034]

[Table 1]

As shown in the table, the loss characteristic of the conventional polymer waveguide was 2.30 dB / cm, whereas the loss characteristic of the polymer waveguide of the present invention was 0.90 dB / cm. This is due to the absorption loss of the CH group in the structure of the polymer. Further, when the loss characteristics were measured after being left for 1 hour in a thermostat at 100 ° C., the loss characteristics of the conventional polymer waveguide were increased to 3.20 dB / cm, whereas the polymer waveguide of the present invention was increased. Shows almost no change at 0.95 dB / cm, indicating low loss and high heat resistance. This is because the polymer was deteriorated due to being left at 100 ° C. for 1 hour, and the scattering loss increased.

FIG. 3 is a plan view when the polymer waveguide shown in FIG. 1 is applied to a Mach-Zehnder type optical filter.
FIG. 4 is a sectional view taken along line AA of FIG.

The Mach-Zehnder type optical filter 2 shown in FIG.
0 denotes two 3 dB couplers 22 formed on the substrate 21
a, 22b and cores 23a, 23b, 23c, 24a, 24b, 24 connected to the 3 dB couplers 22a, 22b.
c. Two 3 dB couplers 22a and 22b
Metal heaters 26a and 26b are provided on the cladding layer 25 covering the two cores 23b and 24b connecting the two.

The cores 23b and 24b have the same optical path length when the metal heaters 26a and 26b are not energized. At this time, the signal light incident from the input port P1 is emitted from the output port P3, but is not emitted from the output port P4.

However, when one of the metal heaters (for example, 26a) is energized and heated, the heated core 24 is heated.
The apparent optical path length is changed by changing the relative refractive index difference between b and the cladding layer 25, and corresponds to an optical phase of 180 ° between the electrically heated core 24b and the electrically unheated core 23b. When the current (or voltage) of the heated metal heater 26a is adjusted so as to have an optical path length difference near 1/2 wavelength, the signal light is output from the output port P4. At this time, the cladding layer 25 is manufactured by the method of the present invention.
The change in the refractive index of the polymer material used for the temperature with respect to the temperature is caused by the cores 23a, 23b, 23c, 24a, 24b, 24
Since the change in the refractive index of the glass material used for c is much larger, the cores 23a, 23b, 23c, 24a,
The relative refractive index difference between the cladding layers 25 and 24b, 24c can be easily changed, and the optical path length difference can be easily adjusted.

As described above, according to the polymer waveguide of the present invention and the method of manufacturing the same, a polymer waveguide having low loss and high heat resistance can be easily obtained.

That is, a material such as polymethyl methacrylate, polycarbonate, polyimide or the like having a lower refractive index than the core is used around the core using SiO _x N _Y H _Z glass which can obtain a high refractive index relatively easily for the core. By covering with a cladding layer made of, a polymer waveguide having low loss and high heat resistance can be obtained without making it difficult to obtain a core material or complicating the manufacturing process.

Further, a functional waveguide type optical component such as a Mach-Zehnder type optical filter can be easily obtained by utilizing the fact that the refractive index change of the polymer material used for the cladding layer with respect to temperature is large.

[0043]

In summary, according to the present invention, the following excellent effects are exhibited.

By using SiO _X N _Y H _Z glass for the core and using a polymer having a lower refractive index than the core for the cladding layer, it is possible to provide a polymer waveguide having low loss and high heat resistance and a method of manufacturing the same. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view of a polymer waveguide of the present invention.

FIG. 2 is a process chart showing a method for manufacturing the polymer waveguide shown in FIG.

FIG. 3 is a plan view when the polymer waveguide shown in FIG. 1 is applied to a Mach-Zehnder optical filter.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a cross-sectional view of a conventional polymer waveguide.

6 (a) to 6 (f) are process diagrams showing a method for manufacturing the polymer waveguide shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Polymer waveguide 11 Substrate 12 Core 13 Cladding layer

Claims (3)

[Claims] 1. An optical waveguide having a core and a cladding layer formed on a substrate, wherein the core is made of SiO _X N _Y H _Z glass, and the cladding layer is made of a polymer having a lower refractive index than the core. Polymer waveguide. 2. The polymer waveguide according to claim 1, wherein a heater is provided near or inside said core. 3. A core film made of SiO _x N _Y H _Z glass is formed on a substrate, and a WSi film is formed on the core film.
The WSi film is subjected to photolithography and dry etching to form a WSi mask pattern, and the core film is dry-etched using the WSi mask pattern to form a core, and the core has a lower refractive index than the core. A method for manufacturing a polymer waveguide, comprising forming a clad layer by covering with a polymer material having the following.