JPS61215505A - Optical module for optical wavelength multiplex transmission - Google Patents

Abstract

PURPOSE:To perform optical wavelength multiplex transmission using >=2 photoconductor elements by providing a block body which has one end surface slanting at a specific angle between a lens and a photoconductor element, providing an interference film filter on the slanting surface, and utilizing reflection caused by the block body. CONSTITUTION:An optical signal of wavelength lambda3 propagated in an optical fiber 12 for transmission as shown by an arrow 14 enters a rod lens 35. The optical signal of wavelength lambda3 entering the glass block 16 in the shape of a rectangular prism is converted into nearly parallel light, which is passed through the 1st interference filter 21, converged by a lens 23-1 on the photodetection surface of a semiconductor photodetecting element 25, and converted photoelectrically. An optical signal of wavelength lambda2 from a semiconductor light emitting element 25 is converted by a lens 23-2 into parallel light, which is incident on the 2nd interference film filter 22, passed through the 2nd interference film filter 22, and reflected by the 1st interference film filter 21. Then, the light is propagated in the glass block 16 almost along the center axis of the rod lens to enter the rod lens 35, and the light enters the rod lens 35 and is converged into an optical fiber 12 for transmission and propagated as shown by an arrow 13. An optical signal of wavelength lambda1 from a semiconductor emitting element 26 travels in a similar course.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is for optical wavelength multiplexing transmission in which a single optical fiber transmission line is used to transmit optical signals of different wavelengths on the upstream and downstream sides of the transmission line. Regarding optical modules.

[Background of the invention]

Wavelength multiplexing transmission technology in optical fiber communications is important for economicalization. In the wavelength division multiplexing transmission described above, an optical multiplexer/demultiplexer is an essential device.

Conventionally, there is a two-wavelength multiplexer/demultiplexer as shown in Figure 1, which aims to reduce the number of parts and make the optical multiplexer/demultiplexer smaller. ``Multiplexer/Demultiplexer for System'', Research and Practical Application Report, Vol. 32, No. 11 (1983)
, P2375-P2385). 1 and 1' are focusing rod lenses, 2 is a bandpass filter that transmits wavelength λ and reflects wavelength λ, and 3 and 4.5 are optical fibers.

First, the wavelength λ transmitted from the optical fiber 3.

The light beams of λ are each incident on a focusing rod lens 1. At this time, the light having the wavelength λ passes through the bandpass filter 2, is focused by the focusing rod lens 1', and is propagated to the optical fiber 5. On the other hand, the light having the wavelength λ is reflected by the bandpass filter 2, focused by the focusing rod lens 1, and propagated to the optical fiber 4. In such a multiplexer/demultiplexer, multiple converging and converging rod lenses are required, and since optical fibers are used at the input and output ends of the converging rod lenses, the number of parts increases. It had drawbacks. Furthermore, since the diameter of the focusing rod lens is approximately 2 mm, there is the problem that high-precision manufacturing technology is required to arrange the optical fibers and band-pass filters respectively and obtain the desired optical characteristics. be.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an optical module for optical wavelength division multiplexing transmission that is simpler and more economical.

[Summary of the invention]

In the present invention, a lens is provided after the optical fiber, a block body having one end face inclined at a predetermined angle is provided between the lens and the optical semiconductor element, and an interference film filter is provided on at least the inclined surface of the surface of the block body. By using the reflection generated by the block body, optical wavelength multiplexing transmission using two or more optical semiconductor elements can be performed.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the optical module for optical wavelength division multiplexing transmission of the present invention. This is an example of a three-wave multiplex bidirectional transmission optical module. That is, transmission optical fiber 2-2
Wavelength λ inside in the direction of arrow 13.

An optical signal with wavelength λ is propagated in the direction of arrow 14, and an optical signal with wavelength λ is propagated in the direction of arrow 14, respectively. In its configuration, the transmission optical fiber 2-2 is disposed on one end face of a gradient index rod lens 35 having a length of approximately 1/4 pitch. A rectangular parallelepiped glass block I6 is connected to the reflective end surface, the tip end surface of the glass block 16 is made to have a desired inclination angle θ, the first interference film filter 21 is formed on the inclined surface, and the rectangular parallelepiped glass block 16, a second interference film filter 9.22 is formed on the bottom surface, and a third interference film filter 20 (or a total reflection film) is formed on the top surface. A lens 23-1 is placed on the extension line of the central axis of the rod lens.
Semiconductor photodetector (for receiving optical signals at wavelength destination) 24
and a lens 23 after the second interference film filter 22 on a line at an angle of about 20 degrees with respect to the central axis of the rod lens.
-2 semiconductor light emitting device (for emitting optical signal with wavelength λ)
25, and further a lens 23 after the second interference film filter 9
-3 semiconductor light emitting device (for emitting optical signal with wavelength λ)
This is a configuration in which 26 are arranged. The interference membrane filter 9,
Examples of wavelength characteristics of 20, 21, and 22 are shown in Fig. 3 (a) to (
Shown in c). For example, the second interference film filter 9 is a filter that transmits an optical signal of wavelength λ 2 and reflects optical signals of wavelengths λ 2 and λ 2 . Second interference film filter 22. The third interference film filter 20 is a filter that transmits optical signals with wavelengths λ 1 and λ 2 and reflects optical signals with wavelength λ 2 .

The first interference film filter 21 is a filter that transmits an optical signal of wavelength λ 2 and reflects optical signals of wavelengths λ 2 and λ 2 . Next, an outline of the operation shown in FIG. 2 will be described. An optical signal having a wavelength λ that has propagated within the transmission optical fiber 2 in the direction of the arrow 14 enters the rod lens 35 . Since the length of the rod lens 35 is approximately 1/4 pitch, the wavelength λ that passes through the rod lens 35 and enters the rectangular parallelepiped glass block 16
The optical signal of The light is focused and converted into electricity. The optical signal of the semiconductor device element 25 having a wavelength λ is converted into parallel light by a lens (ball lens, hemispherical lens, flat plate microlens, graded index rod lens, etc.) 23-2, and is angularly transmitted to the second interference film filter 22. It is incident at θ (θ = -20). The optical signal of wavelength λ passes through the second interference film filter 22 and is reflected by the first interference film filter 21.

The incident angle of the reflected light to the first interference film filter 21 is θ.
Therefore, the light propagates within the glass block 16 along approximately the central axis of the rod lens and enters the rod lens 35. The beam diameter of the optical signal with wavelength λ is narrowed as it propagates leftward inside the rod lens 35, and the beam diameter of the optical signal with wavelength λ is condensed into transmission optical fiber 2, and semiconductor light emission with 6 wavelengths λ is propagated in the direction of arrow 13. The optical signal of element 26 is 23-2
It is converted into parallel light by a lens 23-3 similar to the above, and enters the second interference film filter 9 at an angle of θ. The second interference film filter 9 passes the optical signal of wavelength λ. wavelength λ
After passing through the second interference film filter 9, the optical signal reaches the third interference film filter 20.
and reaches the second interference film filter 22. However, it is also reflected by this second interference film filter 22 and reaches the first interference film filter 21, but it is further reflected by this first interference film filter 21 and leftward inside the glass block 16 in the direction of the central axis of the rod lens 35. move on. The light then enters the rod lens 35, is condensed into the transmission optical fiber 2 in the same manner as the optical signal of wavelength λ, and propagates within the optical fiber 2 in the direction of the arrow 13.

As described above, three-wavelength multiplexed bidirectional transmission can be performed. In this configuration, as described above.

It is very easy to manufacture because it is only necessary to use a rectangular parallelepiped glass block with a simple structure and form an interference film filter on one end, bottom, and top surface of the block.

In addition, it is small and has a small number of parts, and the semiconductor light emitting device 2
5. Assemble the 26 as the arrangement method is the same.

Mounting and optical axis adjustment are also easier. For example, if the portion 29 surrounded by a dotted line is made as one block, the optical axis adjustment can be completed by adjusting this block in the X and Y directions.

FIG. 4 shows an embodiment of a rectangular parallelepiped glass block 16 used in the present invention. Figure (a) is a front view, (
b) is a top view, (C) is a bottom view, and (d) is a side view. The length ρ, the width Ω, and the height Q can be selected to be arbitrary values. However, α and 12 are preferably approximately equal to or larger than the diameter of the rod lens 35. When the glass block is a rectangular parallelepiped, it is easy to cut and polish the glass block, and mass-produced. Furthermore, the interference film filter can be easily attached and the arrangement is stable.

In particular, it is extremely effective in reducing the cost of optical modules.

The interference membrane filters 9, 20, 21, 22 may be attached to the glass block 16 by direct vapor deposition.
Alternatively, the interference film filter 27 formed on the glass plate 28 shown in FIG. 5 may be bonded to the glass plotter with an optical adhesive.

Next, a specific example of the optical module shown in FIG. 2 will be described. 24 is a light receiving element that receives an optical signal with a wavelength of 1.3 μm, 26 is a semiconductor light emitting device with a wavelength of 0.78 μm, and 25 is a semiconductor light emitting device with a wavelength of 0.88 μm. And θ = 35'.

θ = 20”, Q = 6ma, Q = 4m,
Q was set to 10■.

The invention is not limited to the above embodiments. For example, the second interference film filter 19 is brought to the third interference film filter 20, and the semiconductor light emitting element 2 with the lens 23-3 is
6 after the second interference film filter 19, the optical path length of the semiconductor light emitting device (or light receiving device) 26 can be shortened. The loss can be further reduced.

The rod lens 35 may be a spherical lens.

According to the optical module for optical wavelength division multiplexing transmission configured in the above embodiment, (1) Since the optical signal incident on the interference film filter is configured to reflect all but one desired wavelength, it is possible to reduce loss. be.

(2) Top and bottom surfaces of a rectangular parallelepiped glass block.

An interference film filter is formed on one end surface to reflect light in a zigzag manner, so it can be made smaller.

(3) Since the semiconductor light emitting element and the light receiving element are separated, optical and electrical crosstalk can be suppressed.

(4) Since the interference film filter is formed on the outer periphery of a rectangular parallelepiped glass block, it is easy to manufacture.

The glass block is also easy to manufacture because it has a rectangular parallelepiped shape and only one inclined surface.

(5) Since the interference film filter incidence angles θ of the two semiconductor light emitting devices (or light receiving devices) are equal, they can be integrally configured in an array.

Easy to design, assemble, and implement.

(6) When using a rod lens, if the rod lens is placed in a rectangular parallelepiped-shaped container having the same cross-sectional shape as the glass block, it can be connected to the glass block with high dimensional accuracy, and unnecessary reflections at the connection part can be suppressed.

(7) It has a very simple configuration and is easy to assemble and mount, resulting in low cost.

(8) Since the configuration is such that the reflected light of the light emitted from the semiconductor light emitting element within the optical module does not enter the light receiving element, the amount of near-end crosstalk attenuation can be increased.

There is an effect.

The three-wave multiplex bidirectional transmission optical module shown in FIG. 2 has been described above, but the two-wave multiplex bidirectional transmission optical module shown in FIGS. 6 and 7 also operates on the same principle. In addition,
It is not necessary to provide an interference film filter in front of the semiconductor light emitting device 25 as shown in FIG. The one shown in FIG. 7 is the same as the one shown in FIG. 6 except that a second interference film filter 22 is provided to improve isolation. The one in Figure 8 is the one in Figure 2.
A second interference film filter 19 is provided in place of the interference film filter 20, and a semiconductor light emitting element 26 with a lens 23-2 is provided behind it, and the number of parts is reduced compared to the one shown in FIG. There is an effect.

In the above-mentioned embodiment, the case where there is one semiconductor light-receiving element 24 has been described, but the light-receiving element 2 and the light-emitting element can be freely combined.

〔Effect of the invention〕

According to the present invention, it is possible to provide an optical module for optical wavelength division multiplexing transmission that has low loss, is small in size, and is economical.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the prior art, Fig. 2 is an example of the optical module for optical wavelength division multiplexing transmission of the present invention in the case of three wavelengths, and Fig. 3 is an interference diagram used in the optical module for optical wavelength division multiplexing transmission of the present invention. An example of the wavelength characteristics of a membrane filter, FIG. 4 shows an example of a block body used in the optical module for optical wavelength multiplexing transmission of the present invention,
FIG. 5 is a schematic diagram of a glass plate with an interference film filter, and FIGS. 6, 7, and 8 are other embodiments of the present invention. Explanation of symbols

Claims (1)

[Claims] 1. An optical fiber, a first optical semiconductor element, a lens provided between the optical fiber and the first optical semiconductor element, and an end face having an inclined surface at a predetermined angle. a block body provided on the first optical semiconductor element side so that the other end face is on the lens side; a first interference film filter provided on the inclined surface; An optical device comprising one or more second optical semiconductor elements provided on a side surface of a block body, and a second interference film filter provided between the second optical semiconductor element and the side surface of the block body. Optical module for wavelength multiplexing transmission. 2. The optical module for optical wavelength multiplexing transmission according to claim 1, further comprising a third interference film filter for providing the second optical semiconductor element on one side of the block body. 3. An optical fiber, a first optical semiconductor element, a lens provided between the optical fiber and the first optical semiconductor element, and an end surface having an inclined surface at a predetermined angle on the side of the first optical semiconductor element. a block body provided with the other end face facing the lens; a first interference film filter provided on the inclined surface; and a first interference film filter provided on the side surface of the block body in accordance with a predetermined angle of the inclined surface. and a second interference film filter provided between the N-1 second optical semiconductor elements and the side surface of the block body. Optical module for optical wavelength multiplexing transmission.