JPH01128008A - Optical tuner - Google Patents

Abstract

PURPOSE:To provide an optical tuner having a simple structure capable of receiving only the light of a necessary wavelength from plural wavelengths in a piece of an output optical fiber by providing an angle-adjusting mechanism to a holographic diffraction grating. CONSTITUTION:Five different signals from the input optical fiber 3 are entrained in the light consisting of five different wavelengths and is projected diagonally to the holographic diffraction grating 1 through an aspherical lens 2, by which the light consisting of the five different wavelengths is subjected to wavelength dispersion and is reflected at the angle varying with each wavelength. This light is condensed by the aspherical lens 2 and only the light of one wavelength N in the light of the different wavelengths is focused onto the end face of the output optical fiber 4. The light of the other wavelengths is not projected onto the output optical fiber. The light of the other wavelengths can, therefore, be received by adjusting the angle of the holographic diffraction grating by using the angle-adjusting mechanism consisting of a piezo-electric actuator 5, a fulcrum point 6 and a support 7 to project the light of the required wavelength on a photodetecting element and by converting said light to an electric signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical chainer 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 sawtooth diffraction grating, 32 is a spherical lens, and 33 is a sawtooth diffraction grating.
is an input optical fiber, 34, 35° 36.37.38 is an output optical fiber, 39, 40° 41.42.43 is an optical-to-electrical converter, the spherical lens 42 is connected to the sawtooth diffraction grating 41, It is arranged between the input optical fiber 43 and the output optical fibers 44, 45, 46, 47, 48.

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 sawtooth diffraction grating through the spherical lens 32, the light undergoes wavelength dispersion and is reflected at different angles for each wavelength. The lights are converged by the spherical lens, and the lights with different wavelengths are sent to the output optical fiber 34.
．． The light is received at 35, 36 degrees and 37.38 degrees, and the light-to-electricity converter 3
9, 40 degrees, 41 degrees, 42 degrees, and 43 degrees, respectively, and are converted into electrical signals to obtain wavelength characteristics as shown in FIG. (For example, r1978 Institute of Electronics and Communication Engineers Technical Research Report C578
166, pages 37 to 42) Problems to be Solved by the Invention However, although the above configuration is suitable for receiving multiple wideband signals at the same time, 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 However, due to the high cost of optical-to-electrical converters, there was a need for parts with new functions.

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 light receiving element, an aspherical lens disposed in a space in front of the input optical fiber and the light receiving element, and a space in front of the aspherical lens relative to the optical axis of the input optical fiber. The holographic ink diffraction grating is provided with an angle adjustment mechanism using a piezoelectric actuator.

Effect of the present invention With the above-described configuration, by providing the holographic ink diffraction grating with an angle adjustment mechanism, it is possible to receive only the light of the required wavelength from among a plurality of wavelengths with the output optical fiber. , it is possible to create an optical tuner with a simple 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 holographic diffraction grating,
2 indicates an aspherical 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 holographic diffraction grating 1 via the aspherical lens 2, the light consisting of the five different wavelengths undergoes wavelength dispersion and is reflected at a different angle for each wavelength. Among the lights having different wavelengths, only one light of wavelength N is focused on the end face of the light receiving element 4, and light of other wavelengths is not incident on the light receiving element 4.

Therefore, when receiving light of another wavelength, the angle of the holographic diffraction grating is adjusted using the angle adjustment mechanism consisting of the piezoelectric actuator 5, the fulcrum 6, and the support 7, and the light of the desired wavelength is directed to the light receiving element. incident and converts it into an electrical signal.

FIG. 2 is a diagram showing the wavelength selection characteristics of an optical tuner, as shown in FIG.
By adjusting the angle around , the selected wavelength can be varied from the solid line to the dotted line.

Furthermore, an aspherical lens is used as an imaging component, and imaging characteristics free of spherical aberration can be obtained with a single lens.

Holographic diffraction gratings can be produced more easily and in a shorter time than conventional mechanically scored diffraction gratings.

As described above, according to this embodiment, by attaching an angle adjustment mechanism to a holographic diffraction grating, a conventional optical demultiplexer can have a wavelength selection effect, allowing compact and high-performance optical wavelength division multiplexing transmission. It provides parts with new functions.

In this embodiment, a reflection-type holographic ink diffraction grating has been described, but similar effects can be obtained with a transmission-type holographic diffraction grating.

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 an angle adjustment mechanism to a holographic diffraction grating, and is suitable for broadcast type optical wavelength division multiplexing transmission. New suitable optical components can be created.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an optical tuner in an embodiment of the present invention;
Figure 2 is a characteristic diagram showing the wavelength selection characteristics of the optical tuner;
The figure is a plan view of a conventional optical demultiplexer, and FIG. 4 is a characteristic diagram showing wavelength characteristics. 1... Holographic diffraction grating, 2...
... Aspherical lens, 3 ... Input optical fiber, 4
- Old... Light receiving element, 5... Piezoelectric actuator, 6... Fulcrum, 7... Support. Name of agent: Patent attorney Toshio Nakao 1 person - Holographic concave folding screen 2 - Surface lens 3 - Single fiber optic 4 - Light receiving element 5 - 7th gear 6 - fulcrum 1st Figure 7 - Second figure of S body

Claims (1)

[Claims] one input optical fiber, one light receiving element, an aspherical lens disposed in a space in front of the input optical fiber and the light receiving element, and an aspherical lens arranged in a space in front of the aspherical lens on the optical axis of the input optical fiber. What is claimed is: 1. An optical tuner comprising: a holographic diffraction grating disposed obliquely relative to the holographic diffraction grating, the holographic diffraction grating comprising an angle adjustment mechanism using a piezoelectric actuator.