JPS6076829A - Transmission method using optical fiber - Google Patents

Abstract

PURPOSE:To attain multiplex transmission by providing plural light sources at one end face of an optical fiber and irradiating beams so that they may not align in parallel to each other. CONSTITUTION:Drive circuits 4a-5e drive corresponding semiconductor lasers 4a-4e according to the signal fed from a signal source corresponding to each circuit. The laser light outputted from the laser 4a is made incident to one end face 6 at an incident angle theta1, then refracted at refraction angle theta2. Then the laser light is totally reflected on the interface between a core 2 and a cladding 3. The beams fed from each semiconductor laser have an equal incident angle to the face 6 and are not parallel to each other. Therefore, the light outputted from one end face 8 of the output side is outputted at the same angle as the angle theta1, however, these beams are not parallel to each other. Thus no crosstalk is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transmission method using an optical fiber, and particularly to a multiplex transmission method.

[Prior art]

A wavelength multiplexing transmission method has been considered as a method for transmitting a large number of signals using a single optical fiber.

In other words, each channel is associated with a light source with a different wavelength,
Light from each light source is combined by an optical coupler consisting of a condensing lens and transmitted through a single optical fiber. At the other end of the optical fiber, an optical demultiplexer made of a prism or an interference film is provided to separate each signal again, thereby making multiplex transmission possible.

However, according to this wavelength division multiplexing transmission method, since an optical coupler and an optical demultiplexer are essential components, the configuration not only becomes a duplicate but also inevitably becomes expensive. This has been a major obstacle to the spread of multiplex transmission using optical fibers.

[Summary of the invention]

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a multiplex transmission method using an optical seven-eyeper which has an extremely simple configuration and can be implemented at low cost.

In order to achieve this object, the present invention provides a plurality of light sources near one end face of an optical fiber, so that the light from each light source is incident on the other end face of the optical fiber so that they are not flat. The light corresponding to each light source is received as light that is not parallel to each other.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

1 and 2 are drawings showing a first embodiment of the transmission method according to the present invention), FIG. 1 is a schematic configuration diagram, and FIG. 2 is a side view seen from the direction of arrow A in FIG. 1. be.

Reference numeral 1 denotes an optical fiber, which is composed of a core 2 and a cladding 3. 48 to 4h (only 4a and 4e are shown in FIG. 1) are semiconductor lasers, and drive circuits 5a to 5.
h (only 5a and 5e are shown) are respectively driven to emit laser light.

Laser light output from each of the semiconductor lasers 4a to 4h is incident on one end surface 6 of the optical fiber 1 at a predetermined incident angle θl and toward the central axis of the optical fiber 1. Further, the semiconductor lasers 4a to 4h are arranged radially in the circumferential direction of the optical fiber 10.

Therefore, the laser beams are never parallel to each other.

1a to 7h (only 7a and 7e are shown) are light receiving elements, which are arranged radially along the circumferential direction on the other end face 8 of the optical fiber 1, and semiconductor lasers 4a corresponding to each one
It is positioned to receive light from ~4h.

Next, the operation will be explained.

Drive circuits 5a-5h drive corresponding semiconductor lasers 4&-4h based on signals from corresponding signal sources (not shown). Here, the progression of light will be explained using the laser light output from the semiconductor laser 4a as an example. When the laser light output from the semiconductor laser 4a is incident on the end face 6 at an incident angle θl, it is refracted at a refraction angle θ2. This laser beam further travels and enters the interface between the core 2 and the cladding 3 at an incident angle (i-02), and is totally reflected at the same angle. In this way, the laser beam travels in a zigzag manner through the optical fiber 1, and is incident on the end face 8 at an incident angle θ2. Since the laser beam is refracted at the end face 8, it is emitted to the outside of the optical fiber 1 at an angle of θ1. This laser light enters the light receiving surface of the light receiving element 7a corresponding to the semiconductor laser 4a.

The laser beams output from the other semiconductor lasers 4b to 4h are also received by the corresponding light receiving elements 1b to 7e through a similar process.

Note that the light from each semiconductor laser has the same incident angle with respect to the end face 6, but since they are not parallel to each other, the light output from the output side end face 8 is also output at the same angle as the incident angle θl, but each light are not parallel to each other. Therefore, there is no crosstalk.

In this example, a semiconductor laser is used as the light source because the laser light is coherent light, has excellent straight propagation properties, and is less likely to be scattered when reflected at the interface between the core and the cladding. Also, due to recent technological innovations, semiconductor lasers can be purchased at low cost.

Therefore, the use of any light source such as LFjD does not impede the implementation of the present invention.

Further, although the incident angles from the semiconductor lasers 4a to 4h to the end face 6 are all set to the same value θl, it goes without saying that they do not necessarily have to match. However, when the incident angles are matched, the exit angles at the end face 8 are all matched, so there is an advantage that the arrangement of the light receiving elements is easy.

FIG. 3 is a side view for explaining the second embodiment.

In this figure, the same elements as in the first embodiment described in FIGS. 1 and 2 are given the same reference numerals. This figure shows the side opening of the optical fiber 1 viewed from the end face on the light source side, similar to FIG. 2. In the first embodiment, the semiconductor laser 4 is oriented so that the light output from the semiconductor laser 4 passes through the central axis of the optical fiber 1, but in this embodiment, the light is directed off the central axis of the optical fiber. I'm letting you do it. Even in this case, since the beams are not parallel to each other, each beam can be received independently at the other end face of the optical fiber 1.

FIG. 4 is a schematic configuration diagram for explaining the third embodiment. Elements that are the same as those in the first embodiment are given the same reference numerals.

9a to 9h (only 9a and 9e are shown) are LE
D, and a filter 1 is connected between the end face 6 of the optical fiber 1 and the end face 6 of the optical fiber 1.
0a to 10h (only joa and 10e are shown)
is installed. Each of the LEDs 9a to 9h emits light of a different wavelength, and the filters 10a to 1
0h is for making the light from each LED into a narrower band.

118 to 11h (only 11a and 11e are shown)
is a filter interposed between the end surface 8 of the optical fiber 1 and the light receiving elements 78 to 1h, and each filter has a corresponding LED.
Only the same wavelengths as 9a to 9h are transmitted.

Therefore, filter 10a and filter 11a, filter 10b and filter 11b, . . . , filter 10h and filter 11h each transmit the same wavelength.

The directions of the lights emitted from the LEDs 9a to 9h are not parallel to each other, as in the first and second embodiments described above. According to this embodiment configured in this way, in addition to the direction of the light emitted from the end face 8 of the optical fiber 1, identification is also performed based on the wavelength, which reduces the possibility of crosstalk and reduces the number of channels. can be increased.

In this embodiment, an LED 9 is used as a light source and a filter 10 is used to enhance the monochromaticity of light reception, but it goes without saying that the filter 10 is not necessarily required. Alternatively, a normal lamp may be used as the light source, and the light may be made monochromatic by passing through a filter.

〔Effect of the invention〕

As explained above, in the transmission method using an optical fiber of the present invention, a plurality of light sources are provided near one end face of the optical fiber, and the light from each light source is made to be incident so that they are not parallel to each other. By receiving the light corresponding to each light source as non-parallel light from the other end of the fiber, multiplex transmission is possible.a) Optical coupling that was necessary in conventional wavelength multiplexing transmission methods Since no optical demultiplexer or optical demultiplexer is required, the configuration is extremely simple and multiplex transmission can be performed at low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram for explaining the first embodiment of the present invention, Fig. 2 is a side view as seen from the direction A in Fig. 1, and Fig. 3 is a side view for explaining the second embodiment. 4 are schematic configuration diagrams for explaining the third embodiment. 1... Optical fiber, 4a to 411... Semiconductor laser, 7a to 7h... Light receiving element, 9a, 9e...
・LED, 10a, 10e, 11a, 11e fist e #
++ Filter. Fig. 4 110'/G

Claims (1)

[Scope of Claims] (1) Near one end face of an optical fiber [two or more light sources are arranged, and light is incident from each light source that is not parallel to each other by giving an inclination to the normal direction to the end face. A transmission method using an optical fiber, characterized in that the light is received on the other end face of the optical fiber by the same number of light receiving elements as the light sources in a one-to-one correspondence. (2. In the statement of claim 1, the light source is a light source that irradiates coherent light. (3) In the statement of claim 1, Each light source emits light of a single wavelength, and the wavelength of the light emitted by each light source is different from each other, and the light receiving element is capable of receiving only the wavelength of the light emitted by the corresponding light source. A transmission method using optical fiber.