JPS62115403A - Optical tuner - Google Patents

Abstract

PURPOSE:To receive only the light of a required wavelength among light beams of plural wavelengths by a piece of output optical fiber by providing a rotating mechanism to a plane linear diffraction grating. CONSTITUTION:Five different signals from an input optical fiber 3 are entrained in the light beams consisting of five different wavelengths and are made incident via a lens 2 on the plane linear diffraction grating 1, by which the light beams consisting of the five different wavelengths are subjected to wavelength dispersion and are reflected at the angles varying with each of the wavelengths. The reflected light beams are condensed by the lens 2 and only the light of one wavelength among the light beams of the different wavelengths is focused onto the end face of the output optical fiber 4. The light beams of the other wavelengths are not made incident on the fiber 4. The detection of the light beams of the other wavelengths are, therefore, made possible simply by rotating the plane linear diffraction grating by using the rotating mechanism 5 and making the light beam of the required wavelength incident on the output optical fiber.

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 used in optical fiber transmission as a means of effectively utilizing a single optical fiber to send multiple signals on different wavelengths to increase transmission capacity. ing.

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. 5 shows a conventional optical demultiplexer. In Fig. 5, 51 is a planar linear diffraction grating, 52 is a lens, 53 is an input optical fiber, 54, 55, 56, 57, and 58 are output optical fibers, and 59, 60, 61, 62, and 63 are optical-to-electrical converters. The lens 52 is arranged between the planar linear diffraction grating 51, the input optical fiber 53 and the output optical fibers 54, 55, 56, 57, and 58.

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 53 to the plane linear diffraction grating through the lens 52, the light undergoes wavelength dispersion and is reflected at different angles for each wavelength. The lights are converged by the lens, and the lights with different wavelengths are sent to output optical fibers 54 and 5.
The light is received by 5.
6061, 62, and 63 are converted into electrical signals, respectively. (For example, 1978 Institute of Electronics and Communication Engineers Technical Research Report, C378-16637 - Page 42) Although there are only 17 problems that the invention attempts to solve, with the above configuration, it is difficult to receive multiple broadband signals at once. 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, in which many channels of television signals are transmitted over a single optical fiber. , only one set of optical fiber and opto-electric converter is required, and since the cost of opto-electric 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 serves as an optical receiving side device that is 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 a planar linear diffraction grating and a planar linear diffraction grating that makes light incident on the planar linear diffraction grating and receives light from the planar linear diffraction grating. The optical fiber has one input optical fiber and one output optical fiber arranged between the front characters of the planar linear diffraction grating, and a lens is arranged between the planar linear diffraction grating and the optical fiber. , so that a plurality of wavelengths are incident on the plane linear diffraction grating from the single optical fiber through the lens, and light of a desired wavelength is input to the output optical fiber through the lens. It is equipped with a mechanism to rotate the linear diffraction grating.

Effect of the present invention With the configuration described in 1., by providing a rotation mechanism to a flat linear diffraction grating, only light of a required wavelength from among light of a plurality of wavelengths is received by a single output optical fiber. It is possible to create an optical tuner with a simple structure.

Embodiment F An optical tuner according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an optical tuner added to an embodiment of the present invention. In FIG. 1, numeral 1 indicates a planar linear diffraction grating. 2 indicates I men's.

In the above-mentioned configuration, five different signals from the input optical fiber 3 are put on light consisting of five different wavelengths,
By entering the planar linear grating 1 through the 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. , only the light of one wavelength among the lights of different wavelengths connects the fish collection on the end face of the output optical fiber 4, and the light of other wavelengths is not input to the output optical fiber.

Therefore, when receiving light of other wavelengths, the rotating mechanism 5
The planar linear diffraction grating may be rotated using the .DELTA., and light of a desired wavelength may be incident on the output optical fiber. Reference numeral 6 denotes an optical-to-electrical converter, which converts the light incident on the output optical fiber 4 into an electrical signal.

Figure 2 is a diagram showing the wavelength dispersion of a planar linear diffraction grating.
In a), 21 indicates a diffraction grating, and λ1×λ2<λ3×λ4
<When light with five wavelengths of λ5 is perpendicularly incident on the plane linear diffraction grating, the light of λ1 is θ-arc・sin (λ
1/2 d). Here d is the width of the grid.

therefore,! In order to diffract light having a wavelength of 5 to a position (angle) of λ1 in FIG. 2(a), it is preferable to rotate the plane linear diffraction grating by 00-05-01 as shown in FIG. 2(b).

Figure 3 shows the grid f;! 1N=1/cl (book/1 grave) and the dispersion angle θ and wavelength at λ-800nm are 1001
00n (λ=9000m) and the difference Δθ from the dispersion angle is shown.

As can be seen from FIG. 3, the rotation angle of the diffraction grating normally used in this wavelength range may be 10 degrees.

FIG. 4 is a diagram showing the accuracy of rotation angle and the value of wavelength change when λ=8000 m.

From Figure 4, in order to suppress Δλ to 20 nm or less, Δθ is 10
If Δθ=1 minute, it must be less than 3 nm.
The wavelength change can be suppressed as follows.

For this reason, it is necessary to use a pulse motor whose rotation is easy to control for the rotation mechanism, and to control the rotation at a feed rate of at least 10 minutes or less, preferably with a feed accuracy of 1 minute.

As described above, according to this embodiment, by attaching a rotation mechanism to a planar linear diffraction grating, a conventional optical demultiplexer can have a wavelength selection effect, and a component with a new function for optical wavelength multiplexing transmission can be used. This is what we provide.

In this embodiment, a reflection type diffraction grating has been described, but similar effects can be obtained with a transmission type diffraction grating or one including a mirror system.

Effects of the Invention As described above, the present invention allows an optical tuner to be configured with an optical member having a very simple shape by providing a rotation mechanism to a flat linear diffraction grating, and is suitable for broadcast type optical wavelength division multiplexing transmission. new optical components can be created.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an optical tuner in an embodiment of the present invention;
Figure 2 is a conceptual diagram showing the wavelength dispersion of a planar diffraction grating, Figure 3 is a graph showing the difference Δθ between the number of gratings, the dispersion angle at a wavelength of 800 nm, and the dispersion angle when the wavelength increases by 1100 nm, Figure 4 is a graph showing the accuracy of the rotation angle and the change in wavelength at a wavelength of 800 nm, and FIG. 5 is a perspective view of a conventional optical demultiplexer. ■... Planar linear diffraction grating, 2... Lens, 3... Input optical fiber, 4... Output fiber, 5... Rotation Mechanism, 6...
Optical-electrical converter, 21... Planar linear diffraction grating. Name of agent: Patent attorney Toshio Nakao Haka1/-Ichiko Kokukaitake Gosun? ---Lens, 3-Eleven Power Fiber Otsu-Eleven Yu Ichiyaku Moxibustion Benefits Figure 2 21-Eleven Zi Song LL Bundle Pounded Camellia (α) Figure 3 N ('In,) Figure 4, v (to... procedural amendment ~ = 76 April 10, 1985

Claims (2)

[Claims] (1) A planar linear diffraction grating and one input arranged in a space in front of the planar linear diffraction grating so as to input light into the planar linear diffraction grating and to receive light from the planar linear diffraction grating. an optical fiber and one output optical fiber, and a lens is disposed between the planar linear diffraction grating and the optical fiber, and the planar linear diffraction grating is transmitted from the one input optical fiber through the lens. A light beam characterized by comprising a mechanism for rotating the planar linear diffraction grating so that a plurality of wavelengths are input to the diffraction grating and light of a required wavelength is input to the output optical fiber through a lens. tuner. (2) The optical tuner according to claim (1), wherein a pulse motor is used for the rotation mechanism, and the rotation angle feed accuracy is 10 minutes or less.