JPS61219002A - Diffraction grating - Google Patents

Abstract

PURPOSE:To obtain a diffraction grating which has small loss of light and is manufactured at low cost by arranging plural reflecting elements which are made of a transparent material and has two orthogonal total reflecting surfaces on the beveled surface of a prism made of a transparent material. CONSTITUTION:Plural reflecting elements 6 which are made of a transparent material and has two orthogonal total reflecting surfaces 5 and 6 are arranged on the bevel of the prism 8 made of a transparent material and the internal angle that two total reflecting surfaces 5 and 6 is open in the incidence direction of light 1, which is reflected twice by the two total reflecting surfaces 5 and 6. Surfaces which reflect the incident light 1 are total reflecting surfaces consisting of the transparent material and air and have a high reflection factor and the shape of the formed reflecting element is the shape of the reflecting surfaces as it is, so high-precision reflecting surfaces are formed. Consequently, the loss of light of the diffraction grating it reduced.

Description

[Detailed Description of the Invention] [Summary] A diffraction grating that reflects light on a plurality of total reflection surfaces formed in a transparent material and separates the light into wavelengths. This reduces the loss of light that occurs by increasing the precision of the shape and passing it through a diffraction grating.

[Industrial application field]

The present invention relates to an optical circuit element constituting an optical communication system,
In particular, the present invention relates to a diffraction grating that separates an optical signal consisting of light of a plurality of wavelengths into wavelengths.

Optical communication involves superimposing separate pieces of information on lights of different wavelengths, combining them into a single beam of light, and transmitting it to a remote location through the same optical fiber cable. Therefore, on the receiving side, it is necessary to separate the combined light into wavelengths and extract the information superimposed on each light. In such a system, a diffraction grating is used to separate the combined light into wavelengths, and the smaller the loss of light caused by passing through the diffraction grating, the more advantageous it is in terms of system configuration. Therefore, it is desired to develop a diffraction grating that has low optical loss and can be manufactured at low cost.

[Conventional technology]

FIG. 3 is a side sectional view showing a conventional example of a diffraction grating.

In the figure, the conventional diffraction grating has a stepped diffraction grating main body 3 having a plurality of planes 2 facing the direction of incidence of light 1 shown by an arrow, and the surface of the planes 2 is covered with a coating 4 made of metal such as copper. to increase light reflectance.

[Problem that the invention seeks to solve]

However, because the reflective surface of conventional diffraction gratings is made of metal, a portion of the incident light passes through the reflective surface and is absorbed by the metal coating, resulting in a large loss of light caused by passing through the diffraction grating. There was a problem.

[Means for solving problems]

FIG. 1 shows a side sectional view of a diffraction grating according to the invention.

The above problem is solved by arranging a plurality of reflective elements 7 made of a transparent material and having two orthogonal total reflection surfaces 5 and 6 on the slope of a prism 8 made of a transparent material, as shown in FIG. The diffraction grating of the present invention is configured such that the internal angle formed by the reflective surfaces 5 and 6 is opened in the direction of incidence of the light 1, and the incident light 1 is reflected twice by the two total reflection surfaces 5° and 6. solved by.

[Function] In Fig. 1, the surface that reflects the incident light 1 is a total reflection surface composed of a transparent substance and the atmosphere, and has high reflection efficiency, and the shape of the formed reflecting element becomes the shape of the reflecting surface as it is. It is possible to form a reflective surface with high precision. Therefore, light loss in the diffraction grating can be reduced.

Furthermore, the process of forming a metal film on the surface of the reflective surface is not necessary, and the cost for manufacturing the diffraction grating can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a side cross-sectional view showing an embodiment of the diffraction grating according to the present invention.
Figure 2) is the second embodiment of the junction type diffraction grating, Figure 2 (C).
shows an integral diffraction grating in the third embodiment. The same objects are represented by the same symbols throughout the figures.

In the first embodiment of the present invention shown in FIG. 2(a), a resin layer 9 such as acrylic resin or ultraviolet curable resin is formed on the slope of a prism-shaped glass 8, and the shape of a plurality of reflective elements is engraved. A transfer mold 11 having a curved surface 10 is pressed against the resin layer 9, and the shape of each reflective element is transferred onto the slope of the glass 8.

2), a second embodiment of the present invention includes an injection mold 12 having a surface 10 engraved with the shapes of a plurality of reflective elements.
A resin plate 13 having individual reflective elements formed on one side is molded by injecting acrylic resin, ultraviolet curing resin, etc., and is bonded to the slope of the prism-shaped glass 8.

Regardless of whether the above-mentioned diffraction grating is a transfer type diffraction grating according to the first embodiment or a junction type diffraction grating according to the second embodiment, the diffraction grating according to the present invention Loss can be reduced, and it is suitable for mass production and can be manufactured at low cost.

In addition, in the third embodiment of the present invention shown in FIG. The glass 8 is formed in the same glass.

Such an integrated diffraction grating can also reduce light loss in the diffraction grating and can be manufactured at a lower cost than conventional diffraction gratings.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a diffraction grating that has low optical loss and can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a diffraction grating according to the present invention, FIG. 2 is a side sectional view showing an embodiment of the present invention, and FIG. 2(b) is a junction type diffraction grating in the second embodiment, FIG. 2(C) is an integrated diffraction grating in the third embodiment, and FIG. 3 is a side sectional view showing a conventional example of the diffraction grating. It is. In the figure, 1 is incident light, 5.6 is a total reflection surface, 7 is a reflective element, 8 is prismatic glass, 9 is a resin layer,
10 is the engraving surface, 11 is the transfer mold, 12
13 represents the injection mold, 13 represents the resin plate, and 13 represents the injection mold, respectively. 2 shares a year

Claims (1)

[Claims] A plurality of reflective elements (7) made of a transparent material and having two orthogonal total reflection surfaces (5) and (6) are arranged on the slope of a prism (8) made of a transparent material, and The interior angle formed by surfaces (5) and (6) is opened in the direction of incidence of light (1), and the incident light (1) is reflected twice by the two total reflection surfaces (5) and (6). A diffraction grating characterized by being configured as follows.