JPH01129210A - Optical tuner - Google Patents

Abstract

PURPOSE:To obtain new optical parts suitable for optical wavelength multiplex transmission of a broadcasting type by constituting an optical tuner provided with a moving mechanism to a photodetecitng element. CONSTITUTION:Light consisting of different wavelengths is subjected to wavelength dispersion and is reflected at the angles varying with each wavelength when 5 different signals from the input optical fiber 3 are entrained in the light consisting of the 5 different wavelengths and are projected diagonally to a plane linear diffraction grating 1 via a lens 2. This light is condensed by the lens 2 and only the light of one wavelength N in the light of the respectively different wavelengths focuses on the photodetecting face of the photodetecting element 4. The light of the other wavelength is received by moving the output optical fiber in parallel by the use of the moving mechanism 5 and converting the light to an electric signal. Only the light of the required wavelength from the plural wavelengths is thereby received in a piece of the photodetecting element and the new small-sized and high-performance parts for optical wavelength multiplex transmission are obtd.

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 been developed to increase the signal transmission capacity by effectively utilizing wooden optical fibers to transmit multiple signals on different wavelengths. It is attracting attention and being used as a means to achieve this goal.

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. 2 shows a conventional optical demultiplexer. In Fig. 2, 21 is a planar linear diffraction grating, 22 is a lens, 23 is an input optical fiber, 24, 25° 26, 27, 28 is an output optical fiber, 29.30° 31, 32, 33 is an optical-to-electrical converter. The lens 22 is arranged between the planar linear diffraction grating 21 and the input optical fiber 23 and the output optical fiber 24.25.26.27.28.

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 23 to the plane linear diffraction grating through the lens 22, 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 output to optical fibers 24 and 25.
．． The light is received at 26, 27° 28 and the light-to-electrical converter 29, 3
0.31 degrees and 32.33 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. All that is required is one set of optical fibers and an optical-to-electrical converter (because the cost of optical-to-electrical converters is high, parts with new functions have been desired.

The present invention takes the above-mentioned problems into consideration and provides an optical tuner 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 includes one input optical fiber, one light receiving element, and a space in front of the input optical fiber and one light receiving element. The light receiving element has a lens arranged therein, and a diffraction grating arranged in a space in front of the lens obliquely with respect to the optical axis of the input optical fiber, and the one light receiving element is provided with a moving mechanism.

Effect of the present invention With the above-described configuration, the present invention provides a simple light-receiving element that allows one light-receiving element to receive only the light of the required wavelength from among a plurality of wavelengths by providing a moving mechanism to one light-receiving element. It is possible to create an optical tuner with a structure.

EXAMPLE Hereinafter, an optical tuner according to an example 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, 1 indicates a flat linear diffraction grating, and 2 indicates a lens.

In the above-mentioned configuration, five different signals from the input optical fiber 3 are put on light consisting of five different wavelengths,
By obliquely entering the planar linear diffraction grating 1 through the lens 2, the light consisting of the five different wavelengths undergoes wavelength dispersion and is reflected at a different angle for each wavelength, and is condensed by the lens 2. , among the lights of different wavelengths, only one light of wavelength N is focused on the light-receiving surface of the light-receiving element 4, and light of other wavelengths is not incident on the light-receiving element.

Therefore, when receiving light of another wavelength, the light receiving element may be moved in parallel using the moving mechanism 5 to convert the light of the desired wavelength into an electrical signal.

When there is a large amount of light to be received and the distance the light receiving element has to move is large, it is preferable to use a mechanism that moves on the circumference of the lens so that the light from the light receiving element can easily enter the lens.

As described above, according to this embodiment, by attaching a moving mechanism to the light receiving element, a conventional optical demultiplexer can have a wavelength selection effect, and a new function of compact and high-performance optical wavelength division multiplexing transmission can be realized. It provides parts.

Effects of the Invention As described above, the present invention allows an optical tuner to be constructed from an optical member having a very simple shape by providing a moving mechanism to the light receiving element, and provides a new system suitable for broadcast optical wavelength division multiplexing transmission. Optical components can be created.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an optical tuner according to an embodiment of the present invention, and FIG. 2 is a perspective view of a conventional optical demultiplexer. 1... Planar linear diffraction grating, 2... Lens, 3... Input optical fiber, 4... Light receiving element, 5... Movement mechanism. :iJ

Claims (3)

[Claims] (1) One input optical fiber, one light receiving element, a lens disposed in a space in front of the input optical fiber and one light receiving element, and an optical axis of the input optical fiber in the space in front of the lens. What is claimed is: 1. An optical tuner comprising: a diffraction grating disposed obliquely relative to the light receiving element; and wherein the one light receiving element is provided with a moving mechanism. (2) The optical tuner according to claim (1), characterized in that a parallel movement mechanism is used as the movement mechanism. (3) The optical tuner according to claim (1), wherein the moving mechanism is a mechanism that moves on the circumference of the lens.