JPS6145202A - optical waveguide - Google Patents

Abstract

PURPOSE:To obtain a simpel and convenient optical waveguide which has high precision and low loss by forming a chalcogenite glass layer on a substrate while forming a desired waveguide with an electron beam. CONSTITUTION:The chalcogenite glass thin film 3 formed on the substrate 1 is irradiated with the electron beam 4 to form a specific three-dimensional optical waveguide 5. An organic thin film and/or organic thin film 8 which has a less refractive index than the glass thin film 3 and a thin metallic film 10 on the thin film 8 are provided on the chalocogenite glass thin film 3 where the three-dimensional optical waveguide 5 is formed. When the refractive index of the substrate 1 contacting the chalcogenite glass 3 is smaller than that of the chalcogenite glass, light is confined in the optical waveguide formed in the chalcogenite glass. When the substrate 1 uses Si, etc., having a larger refractive index than the chalcogenite glass, its surface is oxidized to produce SiO2 having a less refractive index than the chalcogenite glass preferably. This optical waveguide provided as mentioned above is simple, convenient, and inexpensive and has high precision and low loss, so this is useful for an optical integrated circuit, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical waveguide, and particularly to an optical waveguide with good light confinement efficiency.

To configure an optical communication system, optical components such as semiconductor radars, photodiodes, light receiving and emitting elements, optical fibers, optical connectors, optical couplers, and optical multiplexers and demultiplexers are essential.

Conventionally, these optical components have been constructed by combining lenses, prisms, diffraction gratings, and the like. Therefore, there were various problems such as the size of purchased parts, mechanical stability, reliability, and economic efficiency.

Furthermore, as systems become more sophisticated and their functions diversify, the number of required parts increases, and the processing and processing of parts increases.
There has been a problem in that assembly accuracy and reliability are increasingly required, making the entire system extremely expensive.

Therefore, a new optical system using four optical wave paths introduced the concept of optical ICs that integrate multiple elements on a single substrate, and various research institutes are working to significantly reduce the size and cost of optical components. It is being considered.

The conventional optical waveguide is disclosed in Japanese Patent Application Laid-Open No. 57-85008. Japanese Patent Application Publication No. 5
LkN4O3 as described in 7-88411
Alternatively, a single crystal thin film of Li=TaOs is deposited on the bottom surface of a substrate with a refractive index lower than that of Fry4 by vapor deposition or sputtering, Rurui or INOLN.
There are other methods such as forming an optical waveguide by diffusing a 40 s substrate k T =, and the latter method is generally widely used.

However, the TA ion diffusion temperature is around 1000°C, and when heat treated at such a high temperature, L, i
, zO will diffuse outward. The refractive index distribution of the optical waveguide has widened, the confinement efficiency of the guided light has deteriorated, the extinction ratio has deteriorated, and the connection loss with the fiber has increased.

Furthermore, in order to form the above-mentioned optical waveguide, high-temperature operation is required, and many manufacturing steps are required, resulting in poor productivity. Furthermore, since there is a large difference in refractive index at the contact portion between the optical waveguide and air, the loss caused by scattering in the optical waveguide becomes a power intensifier.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an optical waveguide with low loss and a simple manufacturing process.

[A essential point of the invention]

The present invention relates to a chalcogenide glass (s) formed on a substrate.
J! ! A predetermined three-dimensional optical waveguide is formed by irradiating a single beam onto This is achieved by using an optical waveguide composed of a thin film and a thin gold film formed on the thin film.

The materials K used in the present invention will be explained below. The substrate is (a) silicon such as single crystal silicon or polycrystalline silicon (6QaAj, I?LP, I?lA).

Semiconductors such as (c) LLNbOs, L=TaO
Optical crystal materials such as (d) silica glass such as quartz glass, virex glass, and cracked glass are used. The refractive index of the above substrate is 5.4 in the case of silicon α)
〜3.5I Clause Semiconductor &3〜Technical 6', G) Optical Crystal Case Z1〜2.6. In the case of d) silica glass, it is 13 to 2.0.

A chalcogenide glass film is provided on the substrate. Chalcogenide glass is a general term for amorphous materials containing sulfur, selenium, and tellurium. Specifically, Ag3S
I, AszSes, As5Sey, Ge54゜A
s 2Te s , (jeTe , (je +iAs
5sTe 211821, CclSe, (jes
2, Na25e, etc., the refractive index is 2.1 to 3.1
Out. Among these, Asz8s and AszSea are preferable because they have a large refractive change rate of about 4% when irradiated with an electron beam.

The chalcogenide glass film is formed by a vacuum evaporation method.The evaporation conditions are: substrate temperature 25-100℃, vacuum degree 1x 10-
'~I
oL/sec, preferably substrate temperature 40-60℃
, degree of vacuum 1 x 10''-1 x 10-' mHp,
The film formation rate is 40 to 60X/Sec.

Note that if the refractive index of the substrate in contact with the chalcogen guide glass is smaller than that of the chalcogen glass, light can be confined in the optical waveguide formed in the chalcogen glass. When the substrate is made of silicon such as single crystal silicon or polycrystalline silicon as described above (cL), the refractive index is higher than that of chalcogen glass. For this reason, the surface is oxidized to form a 5LOz (refractive index t47) film having a smaller refractive index than chalcogen glass. 5LOz conversion is pure water α0 (11~Q,
05% nitrogen at a flow rate of 1 to 51. While playing with ＾9, 7
Obtained by heating to 00° to 1200°C. Preferably, it is heated to 800 to 1000° C. while flowing nitrogen containing 2% α005 to CLO, which is pure water, at a flow rate of 2 to 51^9.

When the substrate is in (4) or C6) above, 5LOz, Mρ, etc. with a refractive index of t4 to t7 are formed on the surface by vacuum deposition, coating, CVD, etc. for the same reason as above.

The conditions for vacuum M deposition and sputtering are: substrate temperature 100
~300℃, A hungry lX10-'~5X10-' Parrot Hp
, film formation rate 2~soo, tilt up to J, preferably substrate temperature 150~250°C, degree of vacuum sxin''~5X1
0-'H/, film formation rate 10-100mm, 4G.

As for the CVD conditions, 5AO2fi was formed by oxidizing (02)Ic of monosilane (SAH4). The production temperature is 200 to 800°C and the production rate is 2 to 170/-4G, preferably the production temperature is 550 to 450C and the production rate is 10 to 100A/J4C.

The surfaces of the above (, <) glasses are optically polished. Specifically, the conventionally practiced "i mirror polishing ta<Boy9sing λ" is applied. In Voysing,
An abrasive in which abrasive particles with a size of 1 μm or less are suspended in water, etc., and a soft tool called Bosha are used. When using Se9cum oxide as the abrasive grain and Totebo 9V Ya as the tool, 110
A mirror finish of 0ARtχ or less can be achieved.

Note that when the above (ct) is used as a substrate, it is necessary to take measures to prevent charge accumulation when irradiating the chalcogenide glass film with an electron beam.

As the first method, Inks, 8110
2.

A transparent conductive film such as TAQz and Au is used as a substrate.
ct) by a spin coding method, vapor deposition method, sputtering method, etc. Among them, Inks are particularly important because they can be easily formed into thin films by spin coding. The spin cord conditions are: rotation speed 1000-5000 rpm, m cloth time 10-60 sec, J [thickness 1000-5000
A, preferably rotation speed 2000 to 4000 r
pm, coating time 20~40sec, thickness $2000~
It is 4000A.

The second method is to conduct 'I!' on the chalcogenide glass surface formed on the substrate (ct). It is a method of forming a film. Specific buttons are generally inexpensive and easily available. :
Formed by vacuum evaporation method. The conditions for vacuum deposition are: the substrate temperature is room temperature, the degree of nitrogen is 1XIO-5 to 5X10-'mH1, the film thickness is 50 to 300A, and preferably the degree of vacuum is 5X1O''.
~5x1o-'sH7+, [thickness 100~2ooX tel.

In the second method, after forming a desired three-dimensional optical waveguide in chalcogenide glass using an electron beam, it is necessary to remove the waveguide film using a method such as cutting or f-ing.

The method for forming a three-dimensional light guide path using chalcogenide glass is to
A chalcogenide glass is irradiated with an electron beam, preferably an electron beam having an acceleration voltage of 25 to 30 KV and a spot diameter of α2 to 0.5 μm, using an electron beam drawing device.

The thin film formed on chalcogenide glass is an organic or inorganic thin film having a lower refractive index than chalcogenide glass. Organic thin films include Evokin resin, Frethane resin, polyester resin, polyimide resin, polymethyl methacrylate, chloromethylated polystyrene, organic resist materials for each building used in semiconductor FD911C, and photocurable Ac91 material. .

On the other hand, as inorganic materials, MJ'F2, ZrCh,
CeFs.

5AO2,Aj! zOs, ZnS, 8LO, CaF2
, MIO, CtlS, etc.

? The refractive index of these materials is t3~zO, which is lower than the refractive index of chalcogen glass. Among them, polymethyl methacrylate, chloromethylated polystyrene, SL02
1M10 etc. are preferable.

Thin films can be formed using a spin code method for organic compounds, and a vacuum evaporation method, sputtering method, ion blating method, etc. for inorganic compounds.

These thin films have the effect of efficiently guiding light to a three-dimensional optical waveguide formed by irradiating chalcogenide glass with an electron beam.

Specifically, in the case of an organic thin film, the spinner rotation speed is 1000
-4000 rpm, time 211-60 seconds, preferably spinner rotation speed 2000-3000 rpm, time 30-408 eC. For inorganic thin films, vacuum evaporation fl
For the t method, suba, and 9 ring method, the substrate temperature is 40 to 60.
The conditions were the same as above except for the temperature.

The ion blating method uses a substrate @ 25 to 100°C.

Vacuum i1X10-'~5X10-'a) IP, film formation rate 1%2 osec, preferably substrate temperature 40-60°C, vacuum degree 5X10-4~5X10-'MH
p, the film formation rate is 3''-10X/'Sec.
, Ay, W, Mn, etc. Especially 7V
g.

Since Au is easy to form a thin film, %KJi is required. This metal thin film prevents changes in the refractive index and transmittance of chalcogenide glass with respect to ultraviolet rays, visible light, electromagnetic waves, and K, as well as prevents clouding of chalcogenide glass due to moisture and the film. This is to prevent peeling, etc., and is an essential component in the present invention.

Specifically, the sputtering method is used to reduce the substrate temperature to 25 to 9.
0°C, vacuum filX10~1X10 aHjIF, film formation rate 10~ICI OA/'Sec, film thickness 200~
At 5000 A), preferably the substrate temperature is 40 to 60°C.
, degree of vacuum 5X10-'~5χ1O-8taH1'' *film formation rate 5O-70A/sec, film thickness 1000~300
It's 0A.

Note that the transmission loss, which will be mentioned later, is the total of scattering loss, light confinement efficiency, fiber connection loss, etc.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example t As shown in Figure 1, a silicon single crystal (refractive index 3.4) with a thickness of 400 μl was used as a substrate, and this was placed in an electric furnace and d element containing 0.015% pure water was added. Flow rate 217m1
The substrate was heated at 800° C. while flowing with n, and the surface of the substrate was oxidized to form silicon dioxide 2 (refractive index 1.5) having a thickness of α3μ at the corner.

Next busy, keep the above board 40t+ busy, vacuum level 5X10-'
11) A chalcodechalcogenide glass film 3 (also referred to as an optical waveguide) made by Aszes and having a thickness of 1 μm was vacuum deposited on the silicon dioxide film at a HJ'l film formation rate of 5CJX/SeC.

The refractive index of this chalcogenide glass was 2.41.0 Note that As25s chalcogen glass contains % As and S.
The powder was heated in vacuum at 800° C. to mmt, then rapidly cooled and vitrified.

Next K, Upper Mc: Chalcogenide glass group 3 is irradiated with an electron beam 4 with an acceleration voltage of 254 Hz and a diameter CL of 5 μm to form a three-dimensional optical waveguide 5 with a diameter of about 1 μm as shown in FIGS. 2 and 3. An optical waveguide was obtained.

There are six electron beam irradiation sections with a refractive index of 2.48.

In order to confirm the waveguide characteristics of the three-dimensional optical waveguide 5, the wavelength t3
．． The output light of a semiconductor radar with an output of αm and an output of s tnW was narrowed down to a spot diameter of about 1 μm by a lens system) and coupled to a semi-waveguide 51C. As a result, a good result was obtained with a transport loss rlL24B/am.

Example 2 As shown in FIG. 4, an optical glass (BK-y, quartz glass, refractive index t52) with a thickness of 1 g was used as the IC substrate 1, and this was rotated using a spinner at a rotation speed of 300 rpm.

The above substrate 1 was spin-coated with 1-0 seconds under the conditions of 30 seconds, and prebaked at 100 tons for 10 days.
00℃.

5QmLn Post-baking reduces film thickness to approximately 500O
A's I? A LOs film 6 (refractive index 2.0) was formed.

Next, the substrate was kept at 50°C and the vacuum level was 5 x 10-
5wbHPr film formation rate 6 (the above I?L in Q/sec
An AS2Ses 4 chalcogenide glass film 3 having a thickness of 0.8 μm was vacuum deposited on the Os film. The refractive index of this chalcogenide glass was 2.79.

Next, as shown in FIG. 6 for the fifth factor, an electron beam 4 with an accelerating voltage of 2 skV and a spot diameter α of 5 μm is irradiated onto the chalcogenated glass film to form a three-dimensional leading wave 5 with a width of about 1 μm and an optical waveguide. Obtained. The refractive index of the electron beam irradiation part is 2.8
It was 5.

When the waveguide characteristics of the three-dimensional optical waveguide were measured in the same manner as in Example 1, it was found to be α22 dB/yn, which was good.

Example & A silicon dioxide film 2 was formed on a substrate 1 in the same manner as in Example 1, and on top of this, an Ag3SI JR chalcogenide glass film 3 with a thickness of 1 μm was formed, and a three-dimensional optical waveguide 5 with a width of about 1 μm was formed. Formed.

Next, the substrate 1 is heated to 50°C and the vacuum level is 5 x 10-"
pm9.

A three-dimensional optical waveguide was formed at a film formation rate K of 50 A/sec.

The chalcogenide gas film has a thickness α as shown in the off-graph.
5. An optical waveguide was obtained by forming an un* 5LOz film (refractive index 147) by sputtering.

Then, when the waveguide % of the three-dimensional optical waveguide was measured in the same manner as in Example 1, it was found to be good with a Q of 1 dB/yn.

Example 4 In the same manner as in Example 2, an Inos film with a thickness of about 300A was formed on a substrate made of optical glass (BK-7, quartz glass), and a 0.8 μm thick cQAs2Ses g chalcogenide glass film was formed on this film. A three-dimensional optical waveguide 5 having a width of about 1 μm was formed.

Next, a polymethyl methacrylate (refractive index t49) solution was applied to the chalcogenide glass film on which the three-dimensional waveguide was formed at a rotational speed of 350 rpm for 50 seconds.1. ．． 10 for 10 minutes to form a polymethyl methacrylate film 8 having a thickness of 5000 Å as shown in Figure 8, thereby obtaining an optical waveguide.

Then, when the waveguide characteristics of the three-dimensional optical waveguide 5 were measured in the same manner as in Example 1, the propagation loss was 0 and 11 dBloF.
FL was good.

'1□'' Example 5 As in Example 1, a silicon dioxide film 2 was formed on a substrate 1, and on top of this a chalcodechalcogenide glass film 5 made of AszSs with an IC thickness of 1 μm, and a tertiary layer with a width of about 1 μm. Four original light wave paths 5 were formed.

Next, as in Example 3 of chalcogenide glass construction in which a three-dimensional optical waveguide was formed, a quarium dioxide film 7 was formed.

Subsequently, the substrate 1 was kept at 50°C and the vacuum degree was 5 x 10-'m.
At a HP + deposition rate of 50X/sec, Au g 9 was formed to a thickness of 0.4 μm by sputtering and taring as shown in Figure 9 to obtain four optical wave paths.

Then, when the characteristics of the three-dimensional optical waveguide were measured in the same manner as in Example 1, they were found to be good with @carrier loss Q and j rtf of 310n.

Furthermore, although it was exposed to a chin shine feather meter for 24 hours, the propagation loss did not change after exposure.

Example 6 In the same manner as in Example 2, an optical glass (BK-7, quartz glass) A1 substrate with a thickness of about 60 mm was deposited. A LOsg is formed, and an AszS6xdi chalcogenide glass film with a thickness of α8μ#& is formed thereon, and the width is about 1. A three-dimensional optical waveguide of αm was formed.

Then, as in Example 4, a polymethyl methacrylate film having a thickness of 5000 Å was formed.

The substrate 1 made of the above-mentioned polymethyl methacrylate IIXt was kept at 50° C. and the degree of vacuum was 5×10-swklp.

M was sputtered into the 9th tank and the 10th at a film formation rate of 50 A/sec.
As shown in the figure, an optical waveguide 5 is formed on a polymethyl methacrylate film with a thickness of α4 μm as a U film 10.
I got it.

The waveguide characteristics of the three-dimensional optical waveguide were measured in the same manner as in Example 1 (LlldB, which was good).

Furthermore, it was exposed to an Ic sunshine quasimeter for 24 hours, but the propagation velocity did not change before and after exposure.

Embodiment 1 FIG. 11 shows another embodiment of the present invention, in which three-dimensional optical waveguides 5a and 5b are placed close to each other and is applied as a directional coupler. That is, two adjacent optical waveguides sa and sb
Between Q and Q, the light propagating in one optical waveguide 5a is coupled to the other optical waveguide 5b and K, and optical components essential for the configuration of the optical communication system such as optical switch and f-1 optical modulator are used. becomes.

In order to confirm the performance of the above directional coupler, we used a wavelength of 13 μm.
, the output light of a semiconductor laser with an output of 5#w is reduced to about 1 by the lens system.
It was narrowed down to a diameter of μ and coupled to the optical waveguide 5a.

On the other hand, as a result of measuring the output light from the optical waveguide 5b, the coupling loss o, sdB, and extinction ratio are approximately -s for both transmitted light and coupled light.
Good results were obtained with aelk3.

Embodiment 8 FIG. 12 shows another embodiment of the present invention, which functions as a distributor for distributing the optical signal propagating within the three-dimensional optical waveguide 5a to 5ty-5e. On the other hand, the optical signals propagating in 5b-5e in the opposite path are combined into one,
It also functions as a coupler.

In order to confirm the performance of the above distributor, the wave flame t3μm output 5
The output light of a mW semiconductor laser is ffy1μ with a lens system.
(focusing to a spot diameter of m), and the optical waveguide 5alC was coupled.

As a result of measuring the distributed light on each output boat of 5b-5e, the transmission loss α25ctI3/at le9 distribution deviation 0, 5
A good result of dB was obtained.

〔Effect of the invention〕

As described above, according to the present invention, an optical waveguide that is simpler, more precise, and has lower loss can be formed at a lower cost than conventional products.

Furthermore, the method for producing an optical waveguide disclosed in the present invention will be useful in the formation of optical integrated circuits in the future, including multiplexers and demultiplexers for optical communication.

[Brief explanation of drawings]

Fig. 1.4 is a side view of an optical waveguide showing an embodiment of the present invention, and Fig. 2.5.5.6 is a side view of an optical waveguide showing an embodiment of the present invention. Side and perspective views showing the formed state, off. Figures 8, 9, and 10 are perspective views of optical waveguides showing other embodiments of the present invention, Figure 11 is perspective views of directional couplers as other embodiments of the present invention, and Figure 12 is a perspective view of optical waveguides showing other embodiments of the present invention. FIG. 3 is a perspective view showing an optical splitter/combiner as another embodiment of the present invention. 1...Substrate, 2,7...Iron dihydride film, 5...
Chalcogenide glass film, 4...electron beam, 5...
・Three-dimensional optical waveguide, 6...engine? L05 film, 8...botamethyl methacrylate film, 9-Au film, 10...
~film. Representative Patent Attorney Akio Takashi Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Kaya Figure 7 Figure 8

Claims (1)

[Claims] 1. An optical waveguide comprising a substrate and a chalcogenide glass layer in which a desired waveguide is formed by an electron beam formed on the substrate. 2. An optical waveguide consisting of a substrate, a chalcogenide glass layer on which a desired waveguide is formed by an electron beam, and an organic or inorganic thin film formed on this glass layer. 3. Consisting of a substrate, a chalcogenide glass layer formed on this substrate with a desired waveguide formed by an electron beam, an organic or inorganic thin film formed on this glass layer, and a metal thin film formed on this thin film. optical waveguide. 4. An optical waveguide consisting of a substrate, a conductive layer formed on this substrate, and a chalcogenide glass layer in which a desired waveguide is formed by an electron beam formed on this conductive layer. 5. A substrate, a conductive layer formed on this substrate, a chalcogenide glass layer formed on this conductive layer to form a desired waveguide by an electron beam, and an organic thin film or an organic thin film formed on this glass layer. An optical waveguide. 6. A substrate, a conductive layer formed on this substrate, a chalcogenide glass layer formed on this conductive layer to form a desired waveguide by an electron beam, and an organic or inorganic thin film formed on this glass layer. , an optical path wave path made of a metal thin film formed on this thin film.