JPS6167803A - Optical multiplexer/demultiplexer - Google Patents

Abstract

PURPOSE:To reduce the number of the constituent parts as well as the size and to attain stabilization to vibration from the outside by irradiating electron beams on the thin film of chalcogens glass formed on a substrate so as to form flat microlenses and microgratings. CONSTITUTION:A silicon oxide film 9, the thin film 10 of chalcogens glass having microlenses 13 and microgratings 14-1-14-4 formed by irradiating electron beams, a protective film and a thin metallic film are successively laminated on a silicon substrate 8. Light from an optical fiber 1 is introduced into the glass film 10 through a rodlike lens 4, converted into parallel rays of light through the microlens 13 on the inlet side, and passed through the microgratings 14-1-14-4 to branch the multiplex wavelengths lambda1-lambda4 into the separate wavelengths. When single light having wavelengths lambda1-lambda4 is incident on the glass film 10 from each port, the wavelengths are multiplexed.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to optical wavelength division multiplexing communication, in which light of a plurality of different wavelengths is multiplexed at the transmitting end9 and light is demultiplexed for each wavelength at the receiving end. This invention relates to an optical multiplexer/demultiplexer for optical communications.

(Background of the Invention) Light used for optical communication has a wavelength ranging from 0.8 to 1.5 μm. Optical multiplexers and demultiplexers are essential components in wavelength multiplexing communications, in which light of a certain wavelength is extracted from these bands, and in wavelength multiplexing communications, in which light of multiple wavelengths is multiplexed and transmitted using optical fibers.

Conventionally, an optical multiplexer/demultiplexer has generally used an interference film multilayer filter that has a function of reflecting or transmitting light depending on the wavelength, a diffraction grating that splits light by changing the propagation direction depending on the wavelength, or a prism.

FIG. 1 is an example using a prism. Assuming that light of various wavelengths is propagating within one optical fiber 1 installed on one side, when the light that has been parallelized by the convex lens 2-1 passes through the prism 3, the wavelength dispersion of the refractive index By changing the refraction angle, the convergence position changes depending on the wavelength when exiting the prism 3, so these are connected to convex lenses 2-2.
After passing through the optical fiber, the light of each wavelength is split into multiple optical fibers placed on the output side.

However, since this method generally has low wavelength dispersion of the prism, it is difficult to separate two lights with close wavelengths, it takes time and effort to process the prism, and it is difficult to miniaturize. There are problems such as.

FIG. 2 shows a method of using an interference film filter. In FIG. 2, 6 is an interference film filter, 4 is a rod-shaped lens, and 5 is a glass block. Although this method has the advantage of good wavelength resolution, it requires an interference film made of multiple layers of thin films with a predetermined thickness of about 1 μm or less, and requires an interference film filter with high precision and consistent quality. There is a problem in that it is difficult to manufacture at a mass production pace. Furthermore, it is necessary to use a glass block for the optical bus, which poses problems such as difficulty in downsizing.

FIG. 3 shows a method using a diffraction grating, and 7 in FIG. 3 is a concave diffraction grating. This method generally allows the input fibers to be placed on the same plane, so there is an advantage that the multiplexer/demultiplexer can be made smaller.

However, this method generally has a problem in that the wavelength resolution of the diffraction grating is poor and crosstalk characteristics are poor in practice.

As mentioned above, all of the methods using prisms, interference film filters, and diffraction gratings are constructed by combining them with optical parts such as lenses, and in all of these, the required optical parts are assembled through a predetermined space using adhesive or the like. It will be held and fixed. For this reason, the overall structure tends to become larger and more complicated, and furthermore, it takes time to adjust the angles of each part or the optical axis.

Moreover, it also has the disadvantage that the optical axis may shift due to changes in the external environment or external shocks, which impairs the multiplexing and demultiplexing functions.

Regarding this type of method, for example, Japanese Patent Application Laid-Open No. 55-57
804, JP-A-56-16104. Japanese Unexamined Patent Publication 1985-1967
910.

(Objective of the Invention) The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, have a small number of components, eliminate the need for adhesive bonding of each component, and eliminate the need for angle adjustment.
K provides an optical communication multiplexer/demultiplexer that is stable against external vibrations and can be downsized.

(Summary of the Invention) The present invention provides a chalcogen glass thin film cA formed on a substrate.
) K'WL beam wide beam K'WL multi-formed flat plate microlens and microphone a L/-f ink, and (4) an organic thin film with a small refractive index formed on the above (4). This is a multiplexer/demultiplexer for optical communications, which is constructed from an inorganic thin film (Is') and a metal thin film formed on (B').

It is known that when so-called chalcogen glass containing sulfur is irradiated with an electron beam, the refractive index of the irradiated portion increases.

That is, Journal of Applied Phys.
sics * VoL.

14, A7, P 1079 (1975)
reported that when a λ5285 thin film is irradiated with an electron beam, the refractive index of the irradiated portion increases.

The present invention basically utilizes the change in the refractive index of chalcogen glass by irradiating it with an electron beam as described in the above-mentioned literature, but it will be specifically applied to a multiplexer/demultiplexer for optical communication. This was newly created as a result of considering the problems that arise when

Next, the configuration of the present invention will be explained in detail using the drawings.

FIG. 4 is a sectional view of the device of the present invention, and FIG. 5 is a perspective view. From FIGS. 4 and 5, it can be seen that the device of the present invention has a silicon substrate 8.
It can be seen that it is composed of a silicon oxide film 9, a chalcogen glass thin film 10 in which silicon lenses and micro gratings are formed by electron beam irradiation, an organic or inorganic protective film 11, and a metal thin film 12. In addition, in FIGS. 4 and 5, 4 is a rod-shaped lens for guiding the light incident from the optical fiber 1 to the chalcogen thin film.

FIG. 6 is a diagram for more clearly explaining the optical multiplexing and demultiplexing function of the present invention, and shows the surface of the chalcogen glass thin film from which the organic or inorganic protective film 11 and metal film 12 in FIG. 5 have been removed. This diagram schematically shows the configuration of . In the present invention, multiple wavelengths (λl, λ2
．． (lambda), lambda (lambda) II) are separated into single wavelengths by micro gratings 14-1 to 14-4 formed of chalcogen glass thin films.

The micro grating described above can be obtained by irradiating a chalcogen glass thin film with an electron beam accelerated at 10 to 30 vI. Here, the optical separation function of the micro grating utilizes the phenomenon of light diffraction. Figure 7 shows the refractive index distribution of the micro grating] and shows the distance between the points where the refractive index of the chalcogen glass thin film is maximum and the incident angle of 0 (9th
Condition 2 for Black diffraction (see figure) for wavelength λ
A single wavelength is extracted by reflecting only the wavelengths satisfying nOsinθ=mλ. Here n. is the refractive index of chalcogen glass before electron beam irradiation, and m is a positive integer.

Fig. 6 shows a demultiplexer for demultiplexing four wavelengths λ1 to λ4, with micro grating 14-
t and θ from 1 to 14-4 are manufactured to values convenient for demultiplexing each wavelength using a demultiplexer.

On the other hand, numeral 13 in FIG. 6 is a microlens, which has the function of converting the light collected by the rod-shaped lens and guided into the thin film optical waveguide into parallel light. An example of a microlens is a Fresnel lens. The refractive index distribution is symmetrical with respect to the center of the lens, as shown in FIG. The 7 Renel lens shown in FIG. 8 can be manufactured by irradiating a chalcogen glass thin film with an electron beam to partially increase the refractive index, similar to the micro grating.

Figure 6 shows the case of splitting the light rumored to be λ1 to λ, but on the other hand, if λ1 to λ110 light is injected into each port, it will be possible to split the light by micro grating. It also has the function of a multiplexer, where waved light is injected into a single optical fiber.

Next, the materials that can be used in the present invention and the method for manufacturing the optical multiplexer/demultiplexer will be explained in detail.

First, as a substrate 8 for forming a chalcogen thin film,
Single crystal silicon or polycrystalline silicon can be used. However, when silicon is used, it is necessary to use a material whose surface is Europeanized to form the 5102 thin film 9 because the refractive index of silicon is higher than the refractive index of chalcogen glass.

5102 thin film was thermally oxidized (800-1200
℃) can be easily formed. Here, the refractive index of each material is as follows. Light is confined in a thin film of chalcogen glass 2.3 to 2.6 chalcogen glass 3.46 silicon which is an optical waveguide (8102 film) Therefore, the refractive index of the material in contact with the chalcogen glass (in this case, the silicon dispersion film) needs to be small. Examples of substrate materials other than silicon include compound semiconductors such as GaAs*InP and InAs, as well as LiNbO3 and LiTaO3. Like silicon, these materials have a higher refractive index than chalcogen glass, so they can only be used as a substrate after forming a low refractive index thin film such as 5i029 MgO by vacuum deposition, sputter deposition, CVD, or the like.

Other substrate materials that can be used include optically polished quartz glass, pyrex glass, and crown glass. All of these glasses have a lower refractive index than chalcogen glass, so they can be used as is.

The chalcogen glass that can be used in the present invention refers to all amorphous materials containing sulfur, selenium, and tellurium as elements. A specific example is λa2s5 *AazSe5
+ As2Se2 * G@Sq e
Person52Te5 e GeTe eGe16Aa5
5Tazg82t @Cd's, Ge52, N
There is a25e.

Of these, As2S3 and Aa2St5 are particularly important because their refractive index changes greatly when irradiated with an electron beam.

Since the chalcogen thin film has a higher vapor pressure than general inorganic glass, it can be easily formed by vacuum evaporation.

The film material 11 deposited on the chalcogen glass thin film is an organic or inorganic material with a lower refractive index than chalcogen glass, and specific examples thereof include epoxy resin, urethane resin, polyester resin, polyimide resin, and semiconductor. Various organic resist materials, photocurable acrylic resins, and organic polymer materials used in the production of WLgF
5 e ZrO2* CaF3* SiO2゜゜L20
There are inorganic materials such as 5*ZnS*SiOe CaF2.

The refractive index of these glasses is 1.3 to 2.0, which is smaller than that of chalcogen glass.

(To form these thin films, spin code method is used for organic compounds, sputter deposition method is used for inorganic compounds, C
Examples include VD method and vacuum evaporation method. ) A specific example of the metal thin film formed on the organic or inorganic thin film is t*Au*Ag*W*Mn. Of these, At
, Au is particularly important because it is easy to form a thin film.

Organic or inorganic thin films are used to efficiently guide light within the chalcogen glass, and metal thin films are used to prevent changes in the refractive index and transmittance of the chalcogen glass against various Xa waves, including ultraviolet rays and visible light, and moisture. It is an essential component in the present invention.

(Example of the invention) Next, specific examples will be shown.

Example 1 800 tl: 500 μm thick in an electric furnace heated at K
A multiplexer/demultiplexer substrate was obtained by inserting a silicon single crystal of 100% and blowing pure water into it using nitrogen as a carrier gas, and aging the silicon surface to form an 8102 film of 0.3 μm. The above substrate was heated to about 40°C, and a person 5 was
A 2s5 thin film was formed. The conditions for vacuum evaporation are vacuum degree 5.
×10 mu Hg% film growth rate 50%, and the resulting As285 film thickness was about 1 μm.

Next, the human 18285 thin film was irradiated with an electron beam with a spot diameter of 9.3 μm to produce a micro grating and a Fresnel lens as shown in FIG.

However, in this embodiment, the number of micro gratings is two and the number of 7-Renel lenses is three. The accelerating voltage of the electron beam is 25Kv1 when manufacturing the micro grating.
The voltage was 5 to 25 KV when the Fresnel lens was manufactured. The lattice spacing of the obtained micro grating was 0.961μ
m and 1.04 μm, and the refractive index of the chalcogen glass thin film is n before electron beam irradiation. = 2.41 whereas nrn, X = 2.48. Further, the inclination angle (θ in FIG. 9) of the micro grating with respect to the incident light may be set to 15 degrees. Also, the n of the 7 renel lens. ,n
□1x was also the same as the micro grating, and the focal length of the above lens was 5.0 x.

Coat the above substrate with a thin film of o, a μm o sto.
, when a 4μm0 Au thin film is formed by sputter deposition,
An optical multiplexer/demultiplexer was obtained. The refractive index of SiO was 1.47.

The size of the optical multiplexer/demultiplexer obtained in this way is
It is 0m x 1mm or less, which is extremely small compared to conventional optical multiplexer/demultiplexer.

Using a semiconductor laser in the optical multiplexer/demultiplexer, 1.2 μm and 1 μm
．． When 3 μm light was incident through a fiber or rod-shaped lens, it was confirmed that the Fresnel lens turned it into parallel light, and the micro grating split the light into two types of light. In addition, the 1.2 μm light of the demultiplexer, 1.3
From the μm light emission end, 1.2 μm light and 1.3 μm light
When light is incident, it is multiplexed by the Fresnel lens and micro grating, resulting in 1.2 μm light and 1.3 μm light.
Multiplexed light was injected into the fiber, and its function as a multiplexer was confirmed.

Although the above-mentioned parts were left in a sunshine weather meter for a while, there was hardly any deterioration in the multiplexing/demultiplexing function before and after leaving the parts. For those without SlO thin plate and Au thin film, Sunshine Weather Meter KZ
When left for 4 hours, the refractive index of the chalcogen glass thin film increased, the lens function and crating function disappeared, and it did not work as an optical multiplexer/demultiplexer.

Example 2 Glass substrate with optically polished surface (refractive index: 1.51
) was heated to about 50° C., and an Am2ss5 thin film was formed by vacuum evaporation. The conditions for vacuum evaporation were a vacuum degree of 3XIU-'field Hgs and a film growth rate of 100A/S.
The film thickness of S@U was about 0.8 μm. To this, an electron beam with a spot diameter of 0.311jn was applied to Al12SI.
! A micro grating and a Fresnel lens as shown in FIG. 6 were fabricated by irradiating a 5-thin film. However, in this example, there are two micro gratings and three 7-Renel lenses. The accelerating voltage of the electron beam was 30 KV when producing the micro grating, and 5 to 30 KV when producing the Fresnel lens. The lattice spacing of the obtained micro gratings is 0.830 μm and 0.90 μm.
The refractive index of the A32S@5 thin film is n before electron beam irradiation. nm &
! == 2.85. In addition, the inclination angle of the micro grating with respect to the incident light (θ in Fig. 9) is 1
It was set to 5 degrees. Fresnel lens n. and n Uni are the same as micro gratings, and the focal length of the above lens is 0.
It was 6m.

A 0.5 μm polymethyl methacrylate thin film (refractive index: 1.49) was formed on the above substrate by a spin code method, and then a λg thin film was formed by a sputter deposition method to obtain a optical multiplexer/demultiplexer.

Using a semiconductor laser in the above multiplexer/demultiplexer, 1.21gn and 1
．． When the 3 μmo light was incident through the T-fiber and the Rondo-shaped lens, it was confirmed that the Fresnel lens turned it into parallel light, and the micro grating split it into two kinds of light. Also, the 1.2 μm light of the above demultiplexer, 1.3 μm
From the output end of m light, 1.2μm light and 1.3μm light
When light was input, it was passed through a Fresnel lens and a micro grating, and the multiplexed light of 1.2 and 1.3 μm was injected into the fiber, confirming its function as a multiplexer. It was done.

Although the above-mentioned parts were left in a sunshine weather meter for a while, there was hardly any deterioration in the multiplexing/demultiplexing function before and after leaving the parts. In addition, for the glass without polymethyl methacrylate and human glass thin film, if it is left in the Sunshine Unizumeter for a long time, the refractive index of the chalcogen glass thin film will increase, the lens function and grating function will disappear, and light combining and separation will occur. It did not work as a wave device.

(Effects of the Invention) As described above, according to the present invention, an optical multiplexer/demultiplexer that is smaller than conventional products can be obtained, and since there are fewer components than conventional products, manufacturing costs can be significantly reduced. This has the effect of making it cheaper. Furthermore, the method for manufacturing lenses and gratings that has been clearly demonstrated in the present invention is applicable not only to optical multiplexers and demultiplexers for optical communications.
This will help reduce the size and cost of optical integrated circuits that require light focusing, demultiplexing, and multiplexing.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional optical demultiplexer using a prism, Figure 2 is an enlarged diagram of an optical demultiplexer using a conventional interference film filter, and Figure 3 is a diagram of a conventional optical demultiplexer using a diffraction grating. FIG. 4 is a cross-sectional view of an optical multiplexer/demultiplexer using the chalcogen glass thin film of the present invention, and FIG. 5 is a block diagram of an optical multiplexer/demultiplexer using the chalcogen glass thin film of the present invention. 6 is an explanatory diagram for explaining the operation of the optical multiplexer/demultiplexer using the chalcogen glass thin film of the present invention. FIG. 7 is an explanatory diagram for explaining the operation of the chalcogen glass thin film of the present invention. A diagram showing the refractive index distribution of glass,
FIG. 8 is a diagram showing the refractive index distribution of chalcogen glass in the Fresnel lens portion of the present invention, and FIG. 9 is a diagram showing the angle of incident light with respect to the micro grating. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2-1, 2-2... Convex lens, 3... Prism, 4... Rondo-shaped lens, 5...
・Glass block, 6... Interference film filter, 7...
Concave diffraction grating, 8...Silicon glass thin film, 13...
・Fresnel lens, 14-1, 14-2, 14-3
, 14-4... micro grating, 15...
- Incident light, 16... diffracted light. Agent Patent Attorney Tadashi Akimoto Figure 1 λIA3 Figure 3 λ4 4th w! J Figure 5 Section 7 Figure 8

Claims (1)

[Claims] 1. A substrate, a chalcogen glass thin film formed thereon, a flat microlens and a micro grating provided by irradiating the chalcogen glass thin film with an electron beam, and the chalcogen glass thin film described above. 1. An optical multiplexer/demultiplexer comprising: an organic thin film or an inorganic thin film having a smaller refractive index than the above; and a metal thin film provided on the organic thin film or inorganic thin film. 2. An optical multiplexer/demultiplexer characterized in that the substrate according to claim 1 is silicon with a SiO_2 film or glass whose surface is optically polished. 3. An optical multiplexer/demultiplexer characterized in that the chalcogen glass thin film according to claim 1 is As_2S_3 or As_2Se_3. 4. An optical multiplexer/demultiplexer characterized in that the organic thin film according to claim 1 is polymethyl methacrylate. 5. An optical multiplexer/demultiplexer characterized in that the inorganic thin film according to claim 1 is made of SiO. 6. An optical multiplexer/demultiplexer, characterized in that the metal thin film according to claim 1 is aluminum, gold, or silver.