JPS61103110A - Optical multiplexer and demultiplexer - Google Patents

Abstract

PURPOSE:To permit easy optical axis adjustment, assembly and manufacture by forming diagonally both right and left end faces of a glass body and the end faces of rod lenses disposed to face said body at the same desired angle relative to the axial direction of the rod lenses. CONSTITUTION:Both end faces of the glass block 9 are optically polished diagonally at a desired angle theta1 and interference film filters 10a-10e are deposited by evaporation to the desired position thereof. The value of theta1 is selected fro the range of several degrees to 45 degress. The more preferable value is the range from 10-odd degrees - 20-odd degrees. Since no glass spacers are used, the construction is simple and the size is reduced. Both right and left end faces of the block 9 and the end faces of the rod lenses disposed to face said block are diagonally polished at the same angle and the end faces are adhered together after the formation of the interference film filters thereon and therefore the optical axis adjustment and assembly are made easier.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical demultiplexer that separates and extracts a light beam consisting of a plurality of different wavelengths for each wavelength, or vice versa, in an optical wavelength division multiplexing transmission system. An optical multiplexer that performs
The present invention relates to an optical multiplexer/demultiplexer having both of the above functions, and further to an optical module incorporating a semiconductor light emitting element and a light receiving element.

[Background of the invention]

As part of efforts to expand the application range of optical fiber transmission systems, research on optical wavelength multiplexing transmission systems is being actively conducted. In order to realize the optical wavelength division multiplexing transmission system described above, optical multiplexers and optical demultiplexers that combine and demultiplex lights of different wavelengths are essential devices. As a conventional optical multiplexer/demultiplexer, there is a "multi-reflection optical demultiplexer using an interference film" described in the Proceedings of the National Conference of the Optical and Radio Division of the Institute of Electronics and Communication Engineers in 1980 &280.

Very good characteristics have been obtained. However, conventional devices of this kind have the problem of being expensive, which has been a barrier to expanding the scope of application of optical communication systems. The reason for the high price is that the structure is complex, the number of parts is large, assembly processing and optical axis adjustment are difficult, and mass production is difficult. Invented and applied for an optical multiplexer/demultiplexer with the configuration shown in the figure (Japanese Patent Application No. 58-6996)
0 and Japanese Patent Application No. 5 Jl-130815).

This is achieved by arranging one rod lens with an input fiber on the left and right sides of the glass body and the rod lens with n output fibers arranged in an array approximately parallel to each other. This is a greatly simplified version. This configuration makes it possible to reduce costs. However, in order to expand the application range of optical communication systems,
Further cost reduction is required. For this.

We must continue to reduce the number of parts and simplify optical axis adjustment.

In Figure 1.2, 1a to 1f are optical fibers, 28 to 2f are rod lenses (gradient index type), and 3
a, 3bt 3a', 3b', 3a', 3b'' are glass spacers, 4, 4a, 4b, 4a'.

4b' is a glass flat plate, 5a to 5d, 7a to
7e is an interference film filter, and 68 to 6f are total reflection films.

[Purpose of the invention]

An object of the present invention is to provide a low-cost optical multiplexer/demultiplexer that has a simple structure that allows for easy optical axis adjustment, assembly, and manufacture, and is highly suitable for mass production, as well as an optical module that incorporates a semiconductor light emitting element and a light receiving element. There is a particular thing.

[Summary of the invention]

The present invention utilizes optical multiplexing and demultiplexing in which one rod lens with an input fiber and an array of n rod lenses for output are arranged approximately parallel to each other across a glass body on which an interference film filter is formed. In the glass body, both left and right end faces of the glass body and the end face of the rod lens disposed opposite thereto are formed obliquely at the same desired angle with respect to the axial direction of the rod lens. In addition, in order to facilitate the assembly of the optical axis adjustment 1, a rod lens with a container is used, in which the rod lens is fixed in a container whose cross section is square, rectangular, polygonal, or has a partially straight section. This is what I tried to implement. Furthermore, it is an optical module in which a semiconductor light-emitting element or a light-receiving element is coupled to the exit side of the emitting rod lens directly or via an optical fiber, or further via a lens. By doing so, it is possible to realize a low-cost optical multiplexer/demultiplexer and an optical module that have a simple structure that is easy to manufacture, and are highly suitable for mass production.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG. 3. If semiconductor light emitting elements 11, 12 and 13 each have a different wavelength, an optical multiplexer can be formed and an optical signal can be sent in the direction of the arrow 14. Conversely, if a light receiving element is used in 11, 12, and 13, it can be used as an optical demultiplexer that separates optical signals having different wavelengths (wavelengths λ1, λ2, and λ3) coming from the directions of arrows 15. Further, for example, 11.12 is a semiconductor light emitting device, and 13
If it is a photodetector, it becomes an optical module with optical multiplexing and demultiplexing functions. Here, an example of an optical module having an optical demultiplexing function will be explained. 8a to 8d are graded refractive index rod lenses, each of which has a length of about 1/4 pitch. 9 is a glass block, both end surfaces of which are optically polished obliquely at a desired angle θ, and interference film filters 10a to 10e are placed at desired positions.
is deposited. The value of θ1 is selected from a range of several degrees to 45 degrees. A preferred value is in the range of 10-odd degrees to 20-odd degrees. As can be seen by comparing Figures 1 and 2,
Since there is no glass spacer, it is simple and compact. In addition, both the left and right end faces of the glass block 9 and the end faces of the rod lenses placed opposite thereto are obliquely polished at the same angle, and after forming an interference film filter, they are glued together, simplifying optical axis adjustment and assembly. The operation shown in FIG. 3 will be explained on a first-order basis, which can be simplified. Arrow 1
Wavelength λ1. from 5 directions. λ2. When the optical signal of λ3 enters the optical fiber la, it passes through the rod lens 8a and is converted into substantially parallel light, which enters the glass block 9.

The light is then incident on a 10α interference film filter. The interference film filter 10a passes only the optical signal of wavelength λ1, and
2. 6 Therefore, among the optical signals incident on the interference film filter 10a, only the optical signal with wavelength λ1 passes through and enters the rod lens 8b, and the inside of this rod lens is The light propagates, is focused into the optical fiber lb, and is received by the light receiving element. On the other hand, the optical signals with wavelengths λ□ and λ are reflected by the interference film filter 10a and reach the interference film filter 10d on the opposite side. The interference film filter 10d has a wavelength λ2. If a characteristic is provided to reflect the optical signal of wavelength λ3, the wavelength λ2. The optical signal of wavelength λ is reflected and reaches the interference film filter 10b.If the six interference film filter lobs have the characteristic of passing only the optical signal of wavelength λ2 and reflecting the optical signal of wavelength λLrJL3, the upper The wavelength λ2. which is incident on the interference film filter 10b. Among the optical signals of wavelength λ, only the optical signal of wavelength λ2 passes through and is received by the light receiving element 12, and the optical signal of wavelength λ is reflected and passes through the interference film filter 10e.
reach. If the interference film filter (1 filter loe) has a characteristic of reflecting only the optical signal with the wavelength λ, the optical signal with the wavelength λ that is incident on the interference film filter 10e will be reflected and reach the interference film filter 10c. .Interference film filter 1
If 0(z has a characteristic of allowing only the optical signal of wavelength λ3 to pass through, the light receiving element 13 will receive the optical signal of wavelength λ1.

As shown below, the wavelength λ4. λ2. The optical signals of λ are each demultiplexed, converted into electrical signals by a photoreceiver, and reproduced into desired information signals. The above interference film filters 10a-1
0e can be realized by a conventional band pass filter, short wavelength band pass filter, long wavelength band pass filter, or a combination of the above filters. Length of glass block 9, angle θ1. The interference film filters are arranged at the input rod lens 8a and the output rod lenses 8b and 8c.
.

8d are set to be substantially parallel. Therefore, assembly and optical axis position adjustment are extremely easy.

Next, an example of a rod lens mounting method will be described.

As shown in FIG. 3, each rod lens has one end surface polished to a diagonal optical mirror surface at a desired angle θ1.
Because of the cylindrical shape, the reference position for polishing is unclear. Therefore, when connecting the polished surfaces of each rod lens to the glass block 9, there is a possibility that each rod lens will be connected with angular displacement in the radial direction. As a result, the optical axis is displaced and the optical axis position *a is required, which increases the cost. In order to improve this, as shown in FIG. 4, the rod lens 8 is fixed in a container 14 whose cross section is square or elongated (or polygonal, or even shaped with some straight sections). The method of fixing the rod lens is to vapor-deposit a metal film on the outer periphery of the rod lens and solder it to the container 14 (for example, made of metal), or to fix it to the container 14 by applying an adhesive to the outer periphery of the rod lens. FIG. 4 is a schematic diagram after fixation, with (a) being a front view and (b) being a right side view.

In FIG. 5, the container material in FIG. 4 is the both end surfaces 1 of the rod lens 17.
6.16' were subjected to oblique optical mirror polishing at desired angles θ4 and 8, respectively. (a) is a front view, and (b) is a right side view. In this way, from side 19a to side 19
It is clear that the diagonal polishing was done along b, 19a, 1
9b becomes the polishing reference side. Here, θ8 is taken into consideration to suppress as much as possible the reflected light from the end face 16 returning to the light receiving element side and causing crosstalk, and is normal.

It is set to several degrees or more, more preferably 8 degrees or more.

In FIG. 6, the container material shown in FIG. 5 is rod lenses 17a to 1.
This is an example of an optical module constructed using 7d.

(a) is a front view, (b) is a left side view, (C) is a right side view, and (d) is a bottom view.

The connection between the glass block (square shape) 9 and the rod lens with container is facilitated. Furthermore, since there is no angular displacement during connection, assembly is easy and optical axis adjustment is not required. Furthermore, since the connection is between rectangular objects, it can be accomplished in an extremely short time tm and with almost no adjustment. Note that in FIG. 6, the optical fibers 18a to 18c may not be used.

Namely.

A semiconductor light emitting element or a light receiving element may be placed directly on the end face of the rod lens or via a lens.

FIG. 7 is also another embodiment of the present invention. In this case, extra glass spacers 20a and 20b are used, but instead, the optical fibers of the container rod lenses 17b to 17d can be attached with their side end surfaces aligned, making it easier to accommodate the case.

The invention is not limited to the above embodiments. First, the glass block 9 with an interference film filter is shown as 4a in FIG.

As shown in 4b, two or more layers may be provided to obtain larger near-end and far-end leakage attenuation.The number of wavelength multiplexing can be applied to two or more waves, and optical multiplexing for one-way and two-way transmission can be used. , demultiplexer, and optical module can be configured. A semiconductor laser or a light emitting diode can be used as the semiconductor light emitting element.

The core diameter of the optical fibers 18a to 18c and the refractive index difference between the core and the cladding may be made larger than those of the optical fiber 1a to increase the coupling efficiency with the semiconductor light emitting device and the light receiving device. As shown in the figure, dummy containers 17e, 17f) may be provided to facilitate mounting.Furthermore, the interference film filter may be formed on the end face of the rod lens. Rod lenses with containers 17b, 17c.

For 17d, an integrated type container, that is, a container including three rod lens insertion holes may be used.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a low-cost optical multiplexer/demultiplexer and an optical module that have a small number of parts, one assembly for optical axis adjustment, and a simple structure that is easy to manufacture. . Furthermore, since a polishing reference side is provided when polishing the rod lens after placing it in the container, the rod lens with the container can be mounted with high precision, easily, and in a short time. Furthermore, since the oblique polishing angles of the end face of the glass block and one end face of the rod lens are the same, the polishing can be performed at one time, and the polishing time can be shortened.

[Brief explanation of drawings]

1 and 2 are schematic diagrams of the optical multiplexer/demultiplexer previously proposed by the present inventor, FIGS. 3.6 and 7.8 are embodiments of the optical multiplexer/demultiplexer and optical module of the present invention, and FIG. Figure 5 shows an example of a rod lens with a container used in the present invention. 1 a to 1 f, 18 a to l 8 c - optical fiber, 2 a to 2 f, 8 a to 8 d - CI Hoodons, 3 a, 3 b. 3a', 3b', 3a', 3b'
20a, 20b... Crow spacer, 4, 4a, 4b
, 4a'. 4b'--Glass flat plate, 5a to 5d, 7
a~7e. 10a-10e...interference film filter, 6a-6f...
・Total reflection film, 9...Glass block 11, 12゜1
3...Semiconductor light emitting element or light receiving element, 14°15
...Arrow indicating the propagation direction of light, 16.16'... Oblique calendar surface of the end surface of the rod lens, 17, 17a to 17d.
...Rod lens with container, 19a, 19b...d- ¥2 concave plate (↓) (kF) Fig. f-5

Claims (1)

[Claims] 1. On the left and right sides of the glass body on which the interference film filter is formed, one rod lens with an input fiber and n rod lenses for output arranged in an array are arranged approximately in parallel. The optical multiplexer/demultiplexer is characterized in that both left and right end surfaces of the glass body and the end surfaces of the rod lens arranged opposite thereto are formed obliquely at the same desired angle with respect to the axial direction of the rod lens. Optical multiplexer/demultiplexer. 2. The optical multiplexer/demultiplexer according to claim 1, wherein the rod lens is fixed in a container whose cross section is square, rectangular, polygonal, or has a partially straight section. . 3. An optical module is constructed by connecting a semiconductor light-emitting element or a light-receiving element to the exit side of the emitting rod lens directly or via light, fiber, or lens. The optical multiplexer/demultiplexer according to item 2.