JPS61121011A - Optical wavelength demultiplexer - Google Patents

Abstract

PURPOSE:To reduce the crosstalk by arranging two diffraction gratings so that their diffraction directions are vertical to each other and diffusing circularly the power of scattering due to the grating unevenness of the first and the second diffraction gratings. CONSTITUTION:Two transmission type diffraction gratings 1 and 2 are arranged at a proper interval so that their diffraction directions are orthogonal to each other. If two rays of light A and B different in wavelength are allowed to pass them, the rays A and B are separated from each other by an angle thetain one direction by the first diffraction grating 1 and are separated from each other by the angle theta in the direction orthogonal to said direction by the second diffraction grating 2. That is, an incident light 3 is separated on the same line, and the rays A and B are separated in directions orthogonal to each other, and consequently, the reception interval between the rays A and B is about 2<1/2>theta. Thus, the power per unit area is reduced to reduce the crosstalk between the rays A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an optical wavelength demultiplexer used in wavelength multiplexing optical communications and the like.

[Problems to be solved by conventional technology and invention]

Optical wavelength demultiplexers are used to perform optical demultiplexing in wavelength multiplexing communications, etc., but optical demultiplexers using ordinary diffraction gratings have the problem of not being able to obtain a sufficient degree of separation. .

[Failure to solve the problem]

The present invention provides an optical wavelength demultiplexer with a high degree of separation that solves the above-mentioned problems. This is achieved by an optical wavelength demultiplexer characterized by two diffraction gratings arranged vertically in series.

[For production]

The above-mentioned optical wavelength demultiplexer has two diffraction gratings arranged in series so that their respective optical demultiplexing directions are perpendicular to each other, so that the light separated by the first diffraction grating is further transmitted to the second diffraction grating. Since the beams are separated in the orthogonal direction, a degree of separation that is twice that of a single diffraction grating can be obtained.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of the present invention.
is a perspective view, b is a sectional view taken along line bb in figure a, C is a
It is a cross-sectional view taken along line cc in the figure.

In this embodiment, as shown in FIG. 1, two transmission type diffraction gratings 1 and 2 are arranged so that their diffraction directions are perpendicular and separated by an appropriate distance.

In this embodiment configured in this way, when a plurality of lights of different wavelengths, for example 82 lights of different wavelengths A, pass through, the first
After the lights A and B undergo angular separation of θ by the diffraction grating 1,
The second diffraction grating 2 undergoes a separation of θ in the direction perpendicular to it. That is, in the bb section, the incident light 3 is separated on the same straight line as shown in figure b, and in the cc section, as shown in figure 0, <A, B are separated in the perpendicular direction compared to the case in figure b. Therefore, the light reception interval of A and H is approximately fth θ.

Comparing this embodiment with the case where two diffraction gratings 10°11 are arranged so that their diffraction directions are the same as shown in FIG. 2, the separation angle is approximately 2θ in FIG. As shown in the figure, the scattering 12 due to the unevenness of the diffraction gratings extends linearly and causes crosstalk, but in this example, the diffraction directions of the first and second diffraction gratings are orthogonal, so the power distribution due to scattering is It spreads out in a circular shape, and the power per unit area becomes smaller than in the case of FIG. Therefore, crosstalk between AB is reduced.

〔Effect of the invention〕

As explained above, according to the present invention, by arranging the two diffraction gratings so that their diffraction directions are perpendicular to each other, the power of scattering due to the misalignment of the first and second diffraction gratings can be circularly distributed. can be diffused and reduce crosstalk. Although the present invention uses a transmission type diffraction grating in the embodiment, it goes without saying that it can also be applied to a reflection type.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an embodiment of the optical wavelength demultiplexer of the present invention, and FIG. 2 is a diagram showing an optical wavelength demultiplexer for comparing the effects of the embodiments of the present invention. In the figure, 1.2 represents a diffraction grating, 3 represents incident light, A and B represent two lights with different wavelengths, and θ represents a separation angle.

Claims (1)

[Claims] 1. A light characterized by using two diffraction gratings and arranging them so that the light demultiplexing direction by the first diffraction grating and the light demultiplexing direction by the second diffraction grating are perpendicular. Wavelength demultiplexer. 2. The optical wavelength demultiplexer according to claim 1, wherein a transmission type diffraction grating is used as the diffraction grating. 3. The optical wavelength demultiplexer according to claim 1, wherein the diffraction grating uses a planar diffraction device whose incident light is parallel light.