JPH0527136A - Optical multiplexer/demultiplexer - Google Patents

Abstract

PURPOSE:To offer a small-sized and inexpensive optical multiplexer/ demultiplexer having an optical circulator function in order to perform the duplex multiplex transmission of light among three or more locations. CONSTITUTION:Three or more light input/output ends 509, 510, 511 and 512 are provided, and one optional input/output end 509 out of them and one input/ output end 510 among two input/output ends 510 and 512 adjacent to the input/ output end 509 are optically coupled with specified wavelength lambda1. The wavelengths lambda2, lambda3, and lambda4 with which the other light input/output ends are optically coupled are made all different in the same connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is necessary for performing two-way optical communication at different wavelengths by using an optical fiber between two or more points, and the propagation direction of light is selected depending on the wavelength. It relates to an optical multiplexer / demultiplexer.

[0002]

2. Description of the Related Art In an optical multiplexer / demultiplexer which utilizes the property that the traveling direction of light differs depending on the wavelength, for example, an optical filter using a dielectric multilayer film (hereinafter referred to as a multilayer film filter) is used. A multilayer filter is a transparent glass substrate with multiple layers of dielectrics deposited on it.It has the property of reflecting or transmitting light waves in a certain wavelength range depending on the wavelength dependence of light reflection and refraction characteristics within each layer. Have. The wavelength range is, for example, 10
It means a wavelength width of about nanometer (nm), and means a range of wavelength that does not overlap with other wavelength ranges.
The thickness of the multilayer film itself is on the order of angstroms, which is negligible compared to the transparent glass substrate.

FIG. 1 shows that 1.31 micrometer (μ
m) and an optical multiplexer / demultiplexer for two light waves of 1.55 μm, 101 is an optical connector for inputting / outputting a light wave of wavelength 1.55 μm, and 102 is a light for inputting / outputting a light wave of wavelength 1.31 μm. Connector 103 is an optical connector for inputting / outputting a light wave having a wavelength of 1.31 μm and a light wave having a wavelength of 1.55 μm,
Reference numerals 104, 105 and 106 denote lenses and 107, respectively.
A housing, a multilayer filter 108, and an alternate long and short dash line 109 indicate the optical axis.

The main function of the optical multiplexer / demultiplexer shown in FIG. 1 is represented as shown in FIG. 201 denotes a light wave having a wavelength of 1.31 μm,
Reference numeral 202 denotes a light wave having a wavelength of 1.55 μm, and an arrow indicates a light propagation direction.

The optical multiplexer / demultiplexer having the function shown in FIG. 2 is also realized by a method of bringing two optical fiber cores close to each other and optically coupling between the optical fiber cores. Optical coupling means that light waves are conducted with a sufficiently low loss between two optical channels.

Using the optical multiplexer / demultiplexer as shown in FIG.
If bidirectional optical communication is performed using a light wave of 31 μm and a light wave of wavelength 1.55 μm, its basic configuration is as shown in FIG.
301 is a semiconductor laser with an emission wavelength of 1.31 μm, 302
Is a semiconductor laser having an emission wavelength of 1.55 μm, 303 and 304 are photodetectors, 305 and 306 are the optical multiplexer / demultiplexers shown in FIG. 1, and 307 is an optical fiber. It is clear that the configuration of FIG. 3 enables point-to-point bidirectional wavelength division multiplexing communication.

FIG. 4 shows one form of an optical transmission system for optical two-way communication between four points. 401, 402,
Reference numerals 403 and 404 denote light transmitting and receiving ends, 405,
406, 407 and 408 are optical fibers and 4 respectively
Reference numerals 09, 410, 411 and 412 respectively denote the transmission directions of optical signals, and 413 denotes an optical multiplexer / demultiplexer.

As the optical multiplexer / demultiplexer 413, the optical multiplexer / demultiplexer of FIG. 1 cannot be applied as it is. There is an optical circulator as an optical element that can be used as the optical multiplexer / demultiplexer 413, but it is expensive and leaks a lot of light so that it cannot be put to practical use.

[0009]

SUMMARY OF THE INVENTION Therefore, according to the present invention, in order to perform bidirectional multiplex transmission of light between three or more points, optical multiplexing and demultiplexing necessary for performing bidirectional optical communication using light sources having different wavelengths at each point. It is an object to provide a container.

[0010]

In order to achieve the above object, the optical multiplexer / demultiplexer of the present invention has three or more optical input / output terminals, and any one optical input / output terminal of them. The optical input / output end and one optical input / output end of two adjacent optical input / output ends are optically coupled in a specific wavelength range, and the wavelength ranges are all different.

[0011]

FIG. 5 is a schematic view of the configuration of the first embodiment of the present invention, in which four light waves of different wavelengths λ1, λ2, λ3 and λ4 are combined. 501, 502, 503 and 504
Is a right-angled prism of the same size, and the right-angled portions are arranged sufficiently close to each other. Reference numerals 505, 506, 507 and 508 denote the right-angle prisms 501 and 508, respectively.
A multilayer film attached to 502, 503 and 504. The thickness of the multilayer film is on the order of angstrom, which is negligible in the actual structure. 509, 51
Reference numerals 0, 511 and 512 are light input / output points on the prism surface, and these four points correspond to the vertices of one square.

Although the input and output light waves are shown as two rays for convenience, they are actually one ray. The input and output rays pass through these optical inputs and outputs and are perpendicular to the outer surface of the prism. The multilayer film 505 reflects the light wave of wavelength λ1 and
It is designed to transmit light waves of. Multilayer film 506
Is designed to reflect a light wave of wavelength λ2 and transmit a light wave of wavelength λ1. The multilayer film 507 is designed to reflect a light wave of wavelength λ3 and transmit a light wave of wavelength λ2. The multilayer film 508 reflects the light wave of wavelength λ4,
It is designed to transmit three light waves. According to the present technology for forming a multilayer film, it is easy to give the transmission or reflection characteristics as described above to arbitrary two wavelengths useful for optical communication.

Since the first embodiment has such a configuration,
When the light wave of wavelength λ1 enters the prism from the light input / output point 509, it enters the multilayer film 505 at an incident angle of 45 °, is reflected in a direction perpendicular to the incident direction, and is transmitted through the multilayer film 506.
The light is emitted from the light input / output point 501. Similarly, a light wave of wavelength λ2 incident from 510 is emitted from 511, a light wave of wavelength λ3 incident from 511 is emitted from 512, and a light wave of wavelength λ4 incident from 512 is emitted from 509. That is, FIG. 5 has a function of an optical circulator.
When used as the optical multiplexer / demultiplexer 413, the optical bidirectional communication in four directions becomes possible.

FIG. 6 is a schematic diagram of the configuration of the second embodiment of the present invention. A part of the embodiment shown in FIG. 5 is modified so that the number of light input / output points is three. It is a thing. That is, in FIG. 5, the prisms 503 and 504 are cut to form a trapezoidal prism. The cut surface passes through the point where the light wave of wavelength λ3 reaches the multilayer film 508, and the multilayer films 505 and 5
It is a plane parallel to 07. However, in the embodiment of FIG.
There is no multilayer film corresponding to 508, and the trapezoidal prism is one. 601 emits a light wave of wavelength λ2,
A light input / output point on which the light wave 3 is incident, and 602 is an outer surface of the trapezoidal prism, which is a mirror surface that reflects the light wave.

With such a structure, the light wave having the wavelength λ3 that is incident from the light wave input / output point 601 is reflected by the mirror surface 602 and is emitted from the light wave input / output point 603, and the three-terminal optical circulator. It becomes an optical multiplexer / demultiplexer having a function.

FIG. 7 is a block diagram of the third embodiment of the present invention. Instead of using the prism as in the embodiments of FIGS. 5 and 6, three wavelength optical multiplexers / demultiplexers shown in FIG. 1 are combined. Reference numerals 701, 702, and 703 denote optical multiplexers / demultiplexers, and light waves are input and output through an optical fiber. 704, 705, 706, 707, 708 and 709 are optical fibers.

The optical multiplexer / demultiplexer 701 has a function of optically coupling the light wave of wavelength λ1 between the optical fibers 704 and 707 and optically coupling the light wave of wavelength λ3 between the optical fibers 704 and 709. .. The optical multiplexer / demultiplexer 702 optically couples the light wave having the wavelength λ1 between the optical fibers 707 and 705, and
The two light waves have a function of optically coupling between the optical fibers 705 and 708. The optical multiplexer / demultiplexer 703 optically couples the light wave having the wavelength λ2 between the optical fibers 708 and 706, and
3 has the function of optically coupling between the optical fibers 706 and 709.

Since the embodiments shown in FIGS. 5 and 6 can be produced by the existing thin film technology, they are inexpensive and have a small number of parts and a small size.

The embodiment of FIG. 7 can be realized by combining existing optical multiplexers / demultiplexers and is inexpensive. Further, since the optical multiplexer / demultiplexers 701, 702, and 703 can be configured by all-optical fiber type, they are lightweight as a whole and have low loss.

[0020]

As described above, the present invention provides an optical multiplexer / demultiplexer having an optical circulator function by using different wavelengths, existing technology can be applied, and the number of parts can be increased. Since it is small, it is small, highly functional, and inexpensive. Therefore, according to the present invention, bidirectional optical communication between a plurality of points can be easily realized.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the function of an optical multiplexer / demultiplexer using a multilayer filter.

FIG. 2 is a diagram for explaining the function of an optical multiplexer / demultiplexer.

FIG. 3 is a diagram for explaining bidirectional wavelength division multiplexing communication between two points.

FIG. 4 is a configuration diagram when optical two-way communication is performed between four points.

FIG. 5 is a schematic configuration diagram of an embodiment of a 4-terminal optical multiplexer / demultiplexer according to the present invention.

FIG. 6 is a schematic configuration diagram of an embodiment of a three-terminal optical multiplexer / demultiplexer according to the present invention.

FIG. 7 is a schematic configuration diagram of an embodiment of a three-terminal optical multiplexer / demultiplexer in which a two-wavelength multiplexer / demultiplexer is combined.

[Explanation of symbols]

 101 optical connector 102 optical connector 103 optical connector 104 lens 105 lens 106 lens 107 housing 108 multilayer film filter 109 optical axis 201 light propagation direction 202 light propagation direction 301 semiconductor laser with emission wavelength 1.31 μm 302 emission wavelength 1.55 μm Semiconductor laser 303 Photodetector 304 Photodetector 305 Optical multiplexer / demultiplexer 306 Optical multiplexer / demultiplexer 307 Optical fiber 401 Optical transmitter / receiver 402 Optical transmitter / receiver 403 Optical transmitter / receiver 404 Optical transmitter / receiver 405 Optical fiber 406 Optical fiber 407 Optical fiber 408 Optical fiber 409 Optical signal transmission direction 410 Optical signal transmission direction 411 Optical signal transmission direction 412 Optical signal transmission direction 413 Optical multiplexer / demultiplexer 501 Right-angle prism 502 Right-angle prism 503 Right-angle prism 504 Right-angle prism 505 multilayer film 506 multilayer film 507 multilayer film 508 multilayer film 509 optical input / output point 510 optical input / output point 511 optical input / output point 512 optical input / output point 601 optical input / output point 602 mirror surface 603 optical input / output point 701 optical multiplexer / demultiplexer 702 optical multiplexer / demultiplexer 703 optical multiplexer / demultiplexer 704 optical fiber 705 optical fiber 706 optical fiber 707 optical fiber 708 optical fiber 709 optical fiber

Claims (1)

Claim: What is claimed is: 1. An optical input / output terminal having three or more optical input / output terminals, of which any one optical input / output terminal and two optical input / output terminals adjacent to the optical input / output terminal. An optical multiplexer / demultiplexer, wherein one of the optical input / output terminals is optically coupled in a specific wavelength range, and the wavelength ranges are all different.