JPH01129213A - Optical tuner - Google Patents

Abstract

PURPOSE:To constitute an optical tuner having a simple structure by providing a piece of input optical fiber, a piece of rectangular photodetecting element and a rotating mechanism to a plane linear diffraction grating. CONSTITUTION:A piece of the input optical fiber 3, a lens 2 disposed in the front face of the rectangular photodetecting element 4, and the diffraction grating 1 disposed diagonally with the optical axis of the input optical fiber 3 and the rectangular photodetecting element 4 in the front face of the lens 2 are provided and the rotating mechanism 5 is provided to the diffraction grating 1. The optical tuner having the simple structure which is capable of receiving only the light of a required wavelength from plural wavelengths with a piece of the rectangular photodetecting element 4 is thus constituted by providing the rotating mechanism 5 to the plane linear diffraction grating 1.

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 two optical fibers and transmitting multiple signals on different wavelengths in optical fiber transmission. 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, and 39.40° 41.42.43 is an optical-to-electrical converter. The lens 32 is arranged between the planar linear diffraction grating 31, the input optical fiber 33 and the output optical fibers 34, 35, 36, 37, 38.

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

By inputting light having 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 output to optical fibers 34 and 35.
, 36, 37° 38 and the photoelectric converter 39, 4
They are converted into electrical signals at angles of 0.41° and 42.43°, respectively.

(For example, r1978 Institute of Electronics and Communication Engineers Technical Research Report
C378-166, pages 37 to 42) Problems to be Solved by the Invention However, although the above configuration is suitable for receiving multiple broadband signals at once, it is not suitable for receiving multiple channels of television. When only one signal, or one wavelength, is required at a time, such as broadcast-type optical wavelength division multiplexing, in which the signal is transmitted over a single optical fiber, the optical fiber and optical-to-electrical converter are Because the cost of optical-to-electrical converters is high, parts with new functions were needed.

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 has the following features:
an input optical fiber, a rectangular light-receiving element, a lens disposed in a space in front of the input optical fiber and the rectangular light-receiving element, and a lens disposed in a space in front of the lens; It has a diffraction grating arranged obliquely with respect to the optical axis of the light receiving element, and the diffraction grating is equipped with a rotation mechanism.

According to the present invention, with the above-described configuration, by providing a rotation mechanism to the planar linear diffraction grating, only the light of the required wavelength out of a plurality of wavelengths can be received by a single rectangular light receiving element. An optical tuner with a simple structure can be created.

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, numeral 1 indicates a planar linear diffraction grating. 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 first obliquely entering the planar linear diffraction grating l through the self-lens 2, the light consisting of the five different wavelengths undergoes wavelength dispersion and is reflected at different angles 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 element surface of one rectangular light-receiving element 4, and light of other wavelengths is not incident on the rectangular light-receiving element.

Therefore, when receiving light of another wavelength, the rotation mechanism 5 is used to rotate the planar linear diffraction grating, and the light of the desired wavelength is incident on the rectangular photodetector output optical fiber and converted into an electrical signal. Bye.

Figure 2 is a diagram showing the relationship between the shape of the light receiving element and the wavelength characteristics.
Figure 2 (al, (C1) shows the relationship between the shape of the light receiving element and the imaging light, and Figure 2 (bl, (d+) shows the wavelength characteristic that shows the relationship between the wavelength and the amount of human light.

In Figure 2 (al), 21 indicates a circular light-receiving element, 22 indicates imaging light, and as the wavelength changes, the imaging light changes to 22''.
At the center wavelength, it overlaps with the circular light receiving element 21. In this case, as shown in FIG. 2(b), the wavelength characteristic showing the relationship with the amount of input light as the wavelength of the passband becomes a single peak characteristic.

On the other hand, in the present application shown in FIG. It exhibits good wavelength characteristics as shown in Figure (d).

As described above, according to this embodiment, by attaching a rotation mechanism to a plane linear diffraction grating, a conventional optical demultiplexer can have a wavelength selection effect, and a rectangular photodetector can select a good wavelength. The characteristics can be directly converted into electrical signals,
The project provides components with new functions for compact, high-performance optical wavelength division multiplexing transmission.

Although this example shows the case where the dimension of one side of the light receiving element is the same as the core diameter of the optical fiber, it is advantageous in terms of positioning etc. if the dimension of the - side is larger than the core diameter of the optical fiber. It is.

Effects of the Invention As described above, the present invention provides a rotation mechanism for input optical fibers, one rectangular light-receiving element, and a flat linear diffraction grating. A tuner can be constructed, and a rectangular light-receiving element can be used to directly convert into an electrical signal with good wavelength characteristics, making it possible to create a new optical component suitable for broadcast-type optical wavelength division multiplexing transmission.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an optical tuner according to an embodiment of the present invention, Fig. 2 fa) to fd) are explanatory diagrams showing the shape of the light receiving element and graphs showing wavelength characteristics, and Fig. 3 is a conventional optical demultiplexer. It is a perspective view of a container. 1... Planar linear diffraction grating, 2... Lens, 3... Human powered optical fiber, 4... Rectangular light receiving element, 5...・Rotation mechanism, 21...
...Circular light-receiving element, 22...Imaging light, 23.
...Rectangular light-receiving element. Name of agent: Patent attorney Toshio Nakao, 1 person/-Ichiko MenkijfT Seiko? ---Insinupa 3-Individual power optical fiber゛4-m-Rectangular optical element, ff ---D soft filter purchase/2 ((1) (b) (C2 (d) Manager

Claims (3)

[Claims] (1) One input optical fiber, one rectangular light-receiving element, a lens disposed in a space in front of the input optical fiber and the rectangular light-receiving element, and one input optical fiber in the space in front of the lens. and a diffraction grating arranged obliquely with respect to the optical axis of the rectangular light-receiving element, the diffraction grating comprising a rotation mechanism. (2) The optical tuner according to claim (1), wherein the dimension of one side of the rectangular light receiving element is equal to or larger than the core diameter of the optical fiber. (3) The optical tuner according to claim (1), wherein an antireflection film is attached to the light receiving surface of the rectangular light receiving element.