JPS61144610A - Multiterminal light emitting module - Google Patents

Abstract

PURPOSE:To constitute easily a multiterminal light emitting module with the smaller number of parts and to obtain the higher and stable output thereof by constituting the module in such a manner that the condensing and mixing of light signals are executed by using a one-dimensional distributed index type lens to detect the light signals emitted from a light emitting element. CONSTITUTION:The light signal 4 emitted from the light emitting element 1 is made incident on the input end of the one-dimensional distributed index type lens 2. The lens 2 has the uniform refractive index in the direction of a width W and length L2 and has the refractive index distribution only in the direction of a thickness D. The light signal 4 made incident on the lens 2 is mixed by repeating the total reflection on the side face of the lens 2 and has the uniform intensity distribution at the output end thereof. On the other hand, the refractive index distribution and distances L1, L2 of the lens 2 are so set that the image of the light emitting element 1 which the vertical plane with the light signal 4 is formed at the output end of the lens 2. As a result the belt-like light image 5 of the exit light from the emitting element 1 is made at the output end of the lens 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to transmitting optical signals emitted from one or more light emitting diodes, laser diodes, etc. used in optical communication to a plurality of optical fibers. The present invention relates to a multi-terminal light emitting module that outputs signals by equally branching at a loss.

[Conventional technology]

Conventionally, this type of multi-terminal light-emitting module was produced at the 35th National Conference of the Optical and Radio Division of the Institute of Electronics and Communication Engineers in 1988.
0" is known. FIG. 9 is a schematic configuration diagram showing a conventional multi-terminal light emitting module. In the figure, 1 is a light emitting element such as a light emitting diode or a laser diode, 3 is an optical fiber array in which multiple optical fibers are arranged in a row, 4 is an optical signal emitted from the light emitting element 1, and 8
9 is a lens, 9 is a core of the mixer 11, 10 is a cladding of the mixer 11, and 11 is a mixer with a three-layer structure consisting of the core 9 and cladding 10.

In the multi-terminal light emitting module configured as described above,
An optical signal 4 emitted from the light emitting element 1 is converged by a lens 8) and is input to a core 9 of a mixer 11. The optical signal 4 is mixed with the core 9 of the mixer 11 by repeating total reflection at the joint surface of the cladding 10 of the mixer 11 and the side surface of the core 9 of the mixer 11, both of which have a low refractive index. This results in a uniform intensity distribution at the output end of the core 9 of the mixer 11. Then, an optical fiber array 3 is connected to the output end of the core 9 of the mixer 11 in a positional relationship as shown in FIG.
By splicing the optical signals 4 to multiple optical fibers,
t-Evenly branched. In FIG. 10, 6 is the core of the original fiber, 7 is the cladding of the original fiber, and 9.10 is the core and cladding of the mixer 11, respectively. Also, the 10th
The figure shows that all of the cores 6 of the five original fibers constituting the optical fiber array 3 are included in the core 9 of the mixer 11.

[Problem that the invention seeks to solve]

In the conventional multi-terminal light emitting module as described above, the light emitting element 1, the lens 81, the lens 8, the mixer 11, and the mixer 11
Since the process of aligning the optical fiber array 3 three times is required, there are problems in that it takes a long time and the number of parts increases.

Further, as shown in FIG. 10, since the cross section of the optical fiber at the joint surface between the mixer 11 and the original fiber array 3 is circular, and because the cladding 7 of the original fiber is present,
The optical signal 4 in the shaded area in FIG. 10 was lost. The loss due to this shaded area is called backing fraction loss, and for example, the core diameter of the optical fiber constituting the original fiber array 3 is 50 μm, and the cladding diameter is 62.5 μm.
m, the thickness of the core 9 of the mixer 11 is 50 μm, and @ is 3
00 μm, the loss is as low as about 2.3 dB, which causes a problem in that it reduces the output of the multi-terminal light emitting module.

Furthermore, when a laser diode with a long coherence distance is used as the light emitting element 1, the input end of the mixer 11 by the optical signal 4 is located at the imaging position of the lens 8, so that the reflected light from the input end enters the laser diode. The oscillated light and reflected light interfere with each other, disrupting the oscillation mode and causing an increase in noise. To avoid this, use a laser diode T-500
It is necessary to take measures such as modulating at a high frequency of Mtlz or higher, setting multiple launch modes to shorten the coherence distance, and tilting the input end of the mixer 11 with respect to the optical axis of the output light of the lens 8. It had become. However, the former solution not only complicates the configuration of the optical transmitter including the multi-terminal light emitting module but also makes it expensive, while the latter solution makes the multi-terminal light emitting module itself expensive. was there.

This invention has been made to solve these problems, and includes increasing the output of a multi-terminal light emitting module by reducing backing fraction loss, shortening manufacturing time by reducing the number of axis alignment processes, reducing the number of parts, and emitting light. The purpose of this invention is to obtain a multi-terminal light emitting module that suppresses sources of light returning to elements.

[Means for solving problems]

A multi-terminal light emitting module according to the present invention receives an optical signal emitted from a light emitting element using a one-dimensional gradient index lens, and forms a band-shaped image of the light emitting element at the output end of the one-dimensional gradient index lens. Let me image it.

By joining to this output end an optical fiber array constructed by arranging a plurality of original fibers in a line on the strip-shaped image, the optical signal is evenly split.

[Effect]

In the multi-terminal light emitting device of the present invention, the one-dimensional gradient index lens that receives the optical signal emitted from the light emitting element is used to collect and mix the original signal. Aligning the one-dimensional gradient index lens and aligning the one-dimensional gradient index lens and the optical fiber array only requires two alignment steps, which shortens the work time and reduces the number of parts. can.

〔Example〕

FIG. 1 is a schematic configuration diagram showing a multi-terminal light emitting module which is an embodiment of this invention. In the figure, 1 is a light emitting element such as a light emitting diode or a laser diode, 2 is a one-dimensional gradient index lens, 3 is an optical fiber array in which multiple optical fibers are arranged in a row, and 4 is light emitted from the light emitting element 1. It is an optical signal.

In the multi-terminal light emitting module configured as described above,
The optical signal 4 emitted from the light emitting element 1 enters the input end of the one-dimensional gradient index lens 20 .

The one-dimensional refractive index gradient lens 2 has a uniform refractive index in the width W and length directions, and has a refractive index distribution only in the thickness D direction. In the horizontal plane, the optical signal 4 incident on the one-dimensional gradient index lens 2 is repeatedly totally reflected on the side surface of the one-dimensional gradient index lens 2, as shown in FIG. The intensity distribution becomes uniform at . On the other hand, in the vertical plane, as shown in FIG. L+, Lx'l: Set. As a result, a belt-shaped image 5 of the light emitted from the light emitting element 1 is formed at the output end of the one-dimensional gradient index lens 2, as shown by diagonal lines in Figure WJ4.

Here, the X@ and Y axes in FIG. 4 are the coordinates set at the output end of the one-dimensional refractive index distribution type lens 2. The intensity distributions are as shown in FIGS. 5 and 6, respectively. In each of Figures 5 and 6, the vertical axis indicates relative intensity.
is the width of the image 5 of the emitted light. The value of Id is the refractive index distribution of the one-dimensional refractive index distribution type lens 2 and each distance ML.

It can be adjusted by changing the Lut. As shown in FIG. 7, the emitted light gI5 is connected to the optical fiber array 3 at the output end of the one-dimensional gradient index lens 2. As shown in FIG. Also, as shown in Figure 7, 6,7
are the core and cladding of the optical fibers constituting the optical fiber array 3, and the diagonal plexus portion in FIG. 7 gives the backing horn loss, t-. Figure 8 shows the diameters of each core 6 and cladding 7 of a single fiber of 50 μm and 6 μm, respectively.
2.5 μm", and the width W of the one-dimensional refractive index distribution type
It shows the relationship between the backing fraction loss and the width Id of the image 5 of the emitted light when is set to 300 μm. As is clear from FIG. 8, it can be seen that as the image width dt of the emitted light is made smaller, the backing 7-j traction loss becomes smaller and the output of the multi-terminal light emitting module is improved. For example, if Id is 20 μm, then approximately 1
．． Since the Lp of the conventional multi-terminal light emitting module described above was about 2.3 dB, the output can be improved by about 1.1 dB in the embodiment of the present invention.

Furthermore, as described above, since the one-dimensional gradient index lens 2 has the function of condensing the optical signal 4 and the function of internally mixing the optical signal 4, this one-dimensional gradient index lens 2
By using this, it is possible to reduce the number of small parts, and the alignment process can be performed only twice, reducing the work time.

Furthermore, in the configuration of the multi-terminal light emitting module described above, since the optical signal 4 enters the one-dimensional gradient index lens 2 in a diverging state, even if it is reflected at the input end of the one-dimensional gradient index lens 2. Even if a laser diode is used as the light emitting element 1, since the return light to the light emitting element 1 is suppressed, there is almost no increase in noise and a highly stable multi-terminal light emitting module can be obtained.

In the above-mentioned considerations, it is possible to suppress the light returning to the light emitting element 1 by matching the refractive index at the junction surface between the one-dimensional gradient index lens 2 and the optical fiber array 3. Of course, those skilled in the art can easily consider that it is effective to fill the bonding surface with a matching liquid or a cured product thereof for refractive index matching.

In the above embodiment, the case of a multi-terminal light emitting module in which the number of branches of the optical signal 4 is five has been described, but the present invention is not limited to this, and may be used in a module having an arbitrary number of branches.

In the above embodiment, the diameter of the core 6 and cladding 7 of the original fibers constituting the single fiber array 3t is 50.
Although the case where fibers of .mu.m and 62.5 .mu.m are used has been described, the present invention is not limited thereto, and may be applied to original fibers having arbitrary core diameters and cladding diameters.

Further, in the above embodiment, the case where one light emitting element 1 is used has been described, but the present invention is not limited to this, and may be applied to the case where a plurality of light emitting elements 1 are used.

〔Effect of the invention〕

As described above, the present invention is configured to condense and mix optical signals using a one-dimensional gradient index lens that receives optical signals emitted from a light emitting element in a multi-terminal light emitting module. Therefore, the number of parts per unit can be reduced and the configuration can be simplified. Also, since only two axis alignment steps are required, the work time can be shortened.Furthermore, since the light returning to one light emitting element is suppressed, it is possible to create a multi-terminal light emitting module. This has excellent effects such as high output and stable output.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a multi-terminal light emitting upper joule which is an embodiment of the present invention, and FIGS. 2 and 3 respectively show a one-dimensional gradient index lens in the multi-terminal light emitting module of FIG. FIG. 4 is a schematic diagram showing the progression of an optical signal in a horizontal plane and a vertical plane, and FIG. The 6th reason is. Figure 4 shows the intensity distribution in the X-axis direction and Y-axis direction of the image of the emitted light, and Figure 7 shows the intensity distribution of the lens and optical fiber array on the one-dimensional refractive index distribution in the multi-terminal light emitting module of Figure 1. Figure 8 shows the relationship between the backing fraction loss and the width of the image of the emitted light in the multi-terminal light emitting module of Figure 1, and Figure 9 shows the Joule above the conventional multi-terminal light emitting module. The schematic configuration diagram, FIG. 10, is a diagram showing the joint surface between the mixer and the original fiber array in the multi-terminal light emitting upper Joule shown in FIG. 9. In the figure, 1... Light emitting element, 2... One-dimensional gradient index lens, 3... Optical fiber array, 4... Optical signal, 5... Image of emitted light, 6... Optical fiber core, 7... Optical fiber cladding, 8... Lens, 9
...Mixa core, -10...Mixa paste 2 tsudo,
11...It is a mixer. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) In a multi-terminal light emitting module that branches a signal emitted from a light emitting element such as a light emitting diode or a laser diode to multiple optical fibers and outputs it, the light emitting element receives the optical signal from the light emitting element, and horizontal A one-dimensional gradient index lens that has a function of mixing optical signals in the direction and a function of imaging the light emitting element in the vertical direction, and forms a band-shaped image of the light emitting element at the output end. The optical fibers are connected to the output end of this one-dimensional gradient index lens and have the function of receiving and branching optical signals from the band-shaped image, and a plurality of optical fibers are arranged in a line on the band-shaped image. A multi-terminal light emitting module comprising an optical fiber array. (2) The multi-terminal light emitting module according to claim 1, wherein the width of the band-shaped image of the light emitting element is smaller than the core diameter of the optical fibers constituting the optical fiber array.