JPH01128009A - Optical tuner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical tuner used on the receiving side of optical wavelength division multiplexing transmission in optical fiber communications.

Conventional technology In recent years, optical wavelength division multiplexing transmission technology has become a means of increasing signal transmission capacity by effectively utilizing a single optical fiber to transmit multiple signals on different wavelengths. It is attracting attention and being used as such.

Conventionally, in the above-mentioned optical wavelength division multiplexing transmission, on the receiving side,
Optical demultiplexers were used to split light into wavelengths.

An example of this optical demultiplexer will be described below with reference to the drawings.

FIG. 3 shows a conventional optical demultiplexer. In Fig. 3, 31 is a planar linear diffraction grating, 32 is a lens, 33 is an input optical fiber, 34, 35° 36, 37, 38 is an output optical fiber, 39.40° 41, 42, 43 is an optical-electrical conversion The lens 32 is arranged between the planar linear diffraction grating 31 and the input optical fiber 33 and the output optical fiber 34, 35, 36, 37, 38.

The operation of the optical demultiplexer configured as described above will be explained below.

By inputting light consisting of five different wavelengths from the input optical fiber 33 to the plane linear diffraction grating through the lens 32, the light undergoes wavelength dispersion and is reflected at different angles for each wavelength. The lights converged by the lens and having different wavelengths are outputted to output optical fibers 34 and 35.
．． The light is received at 36,37°38 and the light-to-electrical converter 39,4
0.41 degrees and 42.43 degrees, respectively, are converted into electrical signals.

(For example, 1978 IEICE Technical Research Report C378-166, pages 37-42) Problems to be Solved by the Invention However, with the above configuration, multiple broadband signals are received at a time. However, it is suitable for cases where only one signal, or one wavelength, is required at a time, such as broadcast-type optical wavelength division multiplexing, which transmits many channels of television signals over a single optical fiber. For this, only one set of optical fiber and optical-to-electrical converter is required, and since the cost of the optical-to-electrical converter is high, parts with new functions have been desired.

The present invention takes the above-mentioned problems into consideration and provides an optical chainer that is an optical receiving side device most suitable for broadcast-type optical wavelength division multiplexing transmission.

Means for Solving the Problems In order to solve the above problems, the optical tuner of the present invention has one input optical fiber, one output optical fiber, and optical axes of the input optical fiber and the output optical fiber. the concave diffraction grating is arranged obliquely to the input optical fiber and the output optical fiber; .

Effect of the present invention With the above-described configuration, the concave diffraction grating is provided with a rotation mechanism, so that a single output optical fiber can receive only the light of the required wavelength from among a plurality of wavelengths. It is possible to create an optical tuner with a unique structure.

Embodiment Hereinafter, an optical chainer according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an optical tuner according to the present invention.

In FIG. 1, l indicates a holographic Fourier concave diffraction grating.

In the above-mentioned configuration, five different signals from the input optical fiber 2 are put on light consisting of five different wavelengths,
By obliquely entering the holographic Fourier concave diffraction grating 1, the light consisting of the five different wavelengths undergoes wavelength dispersion, is reflected at different angles for each wavelength, and is condensed, each having a different wavelength. Only the light of one wavelength N among them is focused on the end face of the output optical fiber 3, and the light of other wavelengths is not input to the output optical fiber.

Therefore, when receiving light of another wavelength, the rotation mechanism 4 is used to rotate the holographic Fourier concave diffraction grating and the light of the desired wavelength is input into the output optical fiber. An electrical converter is shown, which converts the light incident on the output optical fiber 3 into an electrical signal.

In particular, at the so-called eagle angle, where the first-order diffraction light returns onto the incident optical axis by the concave diffraction grating, the input optical fiber and the output optical fiber can be disposed in contact with each other, which is advantageous in terms of miniaturization.

Figure 2 is a diagram showing the wavelength dispersion of a holographic Fourier concave diffraction grating. When each light enters a holography/Fourier concave diffraction grating, it is diffracted as shown in the figure.

Therefore, in order to diffract the light with the wavelength of λ5 to the position (angle) of λ1 in Fig. 2 (al), the holographic
As shown in the Fourier plane linear diffraction grating in Figure 2), θ〇−θ
It is preferable to perform a rotation operation by 5-θ1.

In addition, the efficiency beam draw arrangement of a Fourier-shaped diffraction grating provides high efficiency equivalent to that of a sawtooth diffraction grating, making it possible to realize a high-performance optical component.

This Fourier-shaped diffraction grating can be formed by a holographic exposure method, a multiple exposure method, or the like.

Holographic concave gratings are easier to fabricate than traditional mechanically scored gratings.

As described above, according to this embodiment, by attaching a rotation mechanism to the holographic Fourier concave diffraction grating,
A conventional optical demultiplexer can have a wavelength selection effect,
In addition, the eagle type allows input and output optical fibers to be brought close together, providing a small, high-performance component with new functions for optical wavelength division multiplexing transmission.

In this embodiment, a holographic Fourier concave diffraction grating has been described, but similar effects can be obtained with a sawtooth diffraction grating based on the conventional mechanical scoring method.

Effects of the Invention As described above, the present invention provides a rotation mechanism to a holographic Fourier concave line diffraction grating, thereby making it possible to configure an optical tuner with an optical member having a very simple shape without the need for a lens. This makes it possible to create new optical components suitable for broadcast-type optical wavelength division multiplexing transmission.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an optical tuner in an embodiment of the present invention;
FIG. 2 is a conceptual diagram showing wavelength dispersion of a holographic Fourier concave diffraction grating, and FIG. 3 is a perspective view of a conventional optical demultiplexer. 1...Holographic Fourier concave diffraction grating, 2...Input optical fiber, 3...Output optical fiber, 4...Rotation mechanism, 5... ...
- Optical-to-electrical converter, 21...Holographic Fourier concave diffraction grating. /---Holographic Fourier concave diffraction grating? - 3 with human power optical fiber - Output optical fiber 4 - Rotating a structure - 6 - Optical list Keyu school Gu - Kuchi 8 -

Claims (4)

[Claims] (1) It has one input optical fiber, one output optical fiber, and a concave diffraction grating arranged obliquely with respect to the optical axis of the input optical fiber and the output optical fiber, the concave diffraction grating An optical tuner characterized in that the diffraction grating arranged at an eagle angle with respect to the optical axes of the input optical fiber and the output optical fiber is equipped with a rotation mechanism. (2) The optical tuner according to claim (1), wherein a Fourier-shaped concave diffraction grating is used as the concave diffraction grating. (3) The optical tuner according to claim (1), characterized in that a holographic concave diffraction grating is used as the concave diffraction grating. (4) The optical tuner according to claim (1), wherein the concave diffraction grating is arranged at an eagle angle with respect to the optical axes of the input optical fiber and the output optical fiber.