JPS58166320A - Element for optical communication - Google Patents

Abstract

PURPOSE:To obtain an optical demultiplexer having high reliability, by using one common prism for plural optical paths. CONSTITUTION:As for incident light containing wavelength components lambda1-lambda6, which is irradiated to a filter 2a through an optical fiber 5g, a condensing rod lens 4, a prism 7 and a glass plate 1, only the lambda1 component is led to a fiber 5a, other light is reflected and is irradiated to a filter 2b, only the lambda2 component is led to a fiber 5b, and thereafter, the light is demultiplexed to each wavelength light in the same way. The prism for fixing each condensing rod lens 4a-4f is constituted of each common one 3, 3' and 7 as to each rod lens, and the number of prisms is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide an optical communication device that is easy to manufacture and has high reliability by using a common prism for a plurality of optical paths.

With the recent development of optical communication technology, wavelength division multiplexing transmission for the purpose of large-capacity transmission has attracted attention, and the practical application of optical multiplexers and demultiplexers is expected. Multiplexers and demultiplexers for optical communication include methods using gratings, methods using filters, and methods using prisms. A method using a filter is suitable for multiplexing light emitting diodes (LEDs) with a relatively wide emission spectrum width.An example of a multiplexer/demultiplexer using a 0 filter has the structure shown in Figure 1. . 1 in Figure 1
are parallel glass plates, 2a to 2f are optical filters formed on the glass plates, 3a to 3f are prisms fixed on the parallel glass plate 1, 4a to 4f are focusing rod lenses, and 6
a~6. is an optical fiber.

Now, the light having wavelengths 1 to λ6 entering from the fiber 6d passes through the prism 7 and the parallel glass plate 1 to become a parallel beam and enters the filter 2a. The filter 2a is a bandpass filter that allows only the light with the wavelength λ1 to pass through, and the transmitted light with the wavelength λ1 enters the fiber 6b. The light reflected by the filter 2a enters the filter 2b. filter 2
b is a filter that transmits only light of wavelength λ2.

In this way, the lights with wavelengths λ1 to λ6 are sequentially demultiplexed into the fibers 6a to 6° depending on the difference in wavelength.

However, such a demultiplexer requires one prism plus the number of multiplexed wavelengths, and as the number of wavelengths increases, the number of prisms increases. Also, optical filters 2a to 2
For the purpose of keeping the vapor deposition surface free from scratches, parallel glass plates 6 were bonded in advance to each other, and these were bonded to the parallel flat plate 1. The above configuration has disadvantages in that the number of parts increases, the number of manufacturing steps increases, manufacturing is difficult, and reliability decreases.

The present invention has been made to eliminate the above drawbacks. An embodiment of the present invention will be described below with reference to FIG.

In addition, in order to simplify the explanation, the same parts as in FIG. 1 are given the same numbers. 3b, 3, 13f in FIG. 1 are connected to one common prism 3I; and are similarly constructed from one common prism 3.7.

The incident light containing wavelength components of λ and ~λ6 is now connected to the optical fiber s.
When the light q is irradiated onto the filter 2a through the focusing rod lens 4, prism 7 and glass plate 1, the light becomes λ and is guided to the fiber 6a. On the surface of the filter 2a, components other than the λ2 component are reflected and irradiated onto the filter, and only the λ2 component is guided to the fiber 6b via the prism 3' and the focusing rod lens 4b. C, components other than the component are reflected by the surface of filter 2b and guided to filter 2°, where λ
Only three configurations are introduced into the fiber 6° via a prism 3 and a focusing rod lens 4°. Similarly, the fiber 6d has a λ4 configuration, the fiber 6° has a λ6 component, and the fiber 6
The λ6 component is guided to f.

Note that the convergent rod lens 4 has large aberrations, and when it is configured as a collimated thread, the coupling loss of the fiber increases as the optical distance between the lenses increases. It was considered most important to reduce the optical distance of but,
Nowadays, aberrations have become smaller due to improvements in lenses.
The optical distance between lenses has become less of an important issue. Therefore, for example, if the input fiber 6° and λ1
Even though the optical distance between the light output fibers 68 is somewhat larger than that of the conventional structure, the coupling loss in the collimating thread is almost the same. Furthermore, in this embodiment, the filter 2a
~2f is directly glued to the parallel glass plate 1. Conventional optical filters do not adhere well to the glass plate, and it was thought that it was difficult to process the vapor-deposited filter after it was vapor-deposited, but improvements in vapor deposition technology have made it possible to cut the filter without deteriorating its characteristics. As explained above, according to the present invention, the number of prisms can be reduced, the number of prisms can be further reduced, the number of parts can be reduced, and therefore manufacturing is easy. , it is possible to provide a highly reliable device.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an optical communication device according to a conventional example;
The figure is a schematic diagram of an optical communication device according to an embodiment of the present invention. 1... Glass plate, 26-2f... Filter, 3.3'... Prism, 4a-4f...
...Focusing rod lens, 6a to 6f...
Fiber, 7...prism.

Claims (1)

[Claims] A prism A for the incident light beam is provided on one side of the parallel flat glass.
and a plurality of filters with different wavelengths of the a-filled glass are provided, a plurality of filters with different wavelengths of transmitted light are provided on the other surface of the parallel flat glass, and a plurality of filters on each surface of the parallel flat glass are provided. 61 common winter prisms B and C are arranged, a plurality of light focusing rod lenses are arranged on the prism B corresponding to the filters, and the filters are sequentially reflected on one side of the parallel flat glass. An optical communication device characterized in that the light rays transmitted are parallel to each other.