JPS62121427A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain an optical switch which switch numbers of input and output signals with low insertion loss and low crosstalk by switching light signals by utilizing the fact that the deflection direction of a light beam is controllable with the oscillation frequency of an acoustooptic element. CONSTITUTION:Light emitted by an input optical fiber 1 is converted by a lens 2 into a parallel beam, which enters the acoustooptic element 4. An acoustic wave is propagated in the acoustooptic element 4 by the vibration of a vibrator 6 to change the propagation direction of the light beam passing through the acoustooptic element 4. The (m)th input optical fiber 1 can be connected to an optional output optical fiber 8 by controlling the frequency of the vibrator 6 properly. Further, the light beam is made incident on the 2nd acoustooptic element 5 and the vibration frequency of the vibrator 6 is controlled by a vibra tion frequency control circuit 9 to make the propagation direction of the light beam coincident with the optical axis of an output optical fiber 8, thereby coupling the light beam with the output optical fiber 8 efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an optical switch for switching optical signals.

(Prior art and its problems) Conventional optical switches include mechanical optical switches that change the optical path by moving optical fibers and mirrors, and optical constants of waveguides formed with electro-optic crystals that are controlled by applied voltage. There were electro-optic optical switches that perform switching by changing the All of these are two-manpower/two-output switches, and in order to handle a large number of human outputs, these two-manpower/two-output switches were connected in multiple stages as shown in Figure 1. However, these optical switches inevitably suffer from some degree of insertion loss and crosstalk due to defects in the parts and members used (lenses, mirrors, waveguides, crystals, etc.). When the above-mentioned optical switches are connected in multiple stages as shown in Fig. 1 in order to switch a large number of inputs and outputs, the insertion loss and crosstalk of each optical switch are accumulated, and the S/ of the optical signal passing through the optical switch is The N ratio deteriorates significantly. For this reason, the limit for conventional optical switches is 6 human power and 6 outputs.
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(Object of the Invention) An object of the present invention is to provide an optical switch capable of switching a large number of input/output signals with low insertion loss and low crosstalk.

(Structure of the Invention) The main feature of the present invention is that optical signals are switched by utilizing the fact that the deflection direction of a light beam by an acousto-optic element can be controlled by the vibration frequency of the acousto-optic element. 2
This method differs from conventional technology in which manually operated two-output optical switches are connected in multiple stages in that a single stage optical switch mechanism can switch a large number of optical signals.

(Embodiment) FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, in which 1 is an input optical fiber, 2 and 3 are lenses, 4 and 5 are acousto-optic elements, 6 and 7 are vibrators, and 8 9 is an output optical fiber, and 9 is a vibration frequency control circuit. In this embodiment, there are M manual optical fibers and N output optical fibers.

The operating principle of the present invention will be explained by taking the m-th input optical fiber 1 (llI) as an example. The light exiting the input optical fiber 1 is converted into a parallel beam by the lens 2 and then passed through the acousto-optic element 4.
to go into. A sound wave propagates within the acousto-optic element 4 due to the vibration of the vibrator 6, and the propagation direction of the light beam passing through the acousto-optic element 4 is changed. Since the deflection direction of the light beam depends on the frequency of the sound wave, the m-th input optical fiber 1 ( 1,) oscillator 60 frequency f = fn (n = 1+ 2+
'-'-'+N) exists. Therefore, if the vibration frequency control circuit 9 controls the frequency of the vibrator 6 so that (=f), the m-th input optical fiber 1
(1,) can be connected to any output optical fiber 8.

By selecting the frequency of the vibrator 6 to be f7, the light beam deflected by the acousto-optic element 4 so as to be connected to the n-th output optical fiber 8 (0, l). , the propagation direction of the light beam does not match the optical axis of the output optical fiber 8, so even if the light is focused by the lens 3, it is not efficiently coupled to the output optical fiber.
The vibration frequency of the vibrator 7 is controlled by the vibration frequency control circuit 9 so that the propagation direction of the light beam coincides with the optical axis of the output optical fiber 8, so that the light beam is efficiently output. The optical fiber 8 is coupled to the optical fiber 8.

In the above explanation, a one-to-one connection was explained, but if the vibrator 6 is vibrated at multiple frequencies at the same time, the output light beam of one human-powered optical fiber 1 will be directed in the direction corresponding to each frequency. Since it can be deflected, it is possible to connect one input optical fiber l to a plurality of output optical fibers 8.

Further, the output light of the 71 optical fibers 1 passes through a plurality of acousto-optic units so that the output light of the 71 optical fibers 1 is polarized in the direction in which the output light of the plurality of input optical fibers 1 is connected to one output optical fiber 8. If the frequencies of the vibrators 6 of the elements 4 are appropriately selected, it is possible to connect a plurality of input optical fibers l to one output optical fiber 8. In this case, the outputs connected such that the propagation directions of the plurality of light beams from the plurality of input optical fibers l deflected by the acousto-optic element 4 respectively coincide with the optical axis of the output optical fiber 8. If the vibrator 7 of the acousto-optic element 5 assigned to the optical fiber 8 is made to vibrate at a plurality of appropriate frequencies,
The plurality of light beams described above are efficiently coupled to the output optical fiber 8.

FIG. 3 is a diagram showing a configuration example of a control circuit for the vibration frequency of the vibrator 6 corresponding to the m-th input optical fiber 1 in the vibration frequency control circuit 9, in which the oscillator 1
0-1.10-2. ...-, 10-N, selector l1m
is built-in. Oscillator 10-L 10-2°-, 1
The frequencies of 0-N are respectively fl+ f2+・-,
f.

is set to . The selector l1m selects one or more frequencies necessary for the required connection between the m-th human-powered optical fiber l and one or more output optical fibers 8 from among these frequencies, and returns them to the signal fiber 12. , is transmitted to the vibrator 6, causing the vibrator 6 to vibrate at a desired frequency. The vibrators 6 corresponding to the other input optical fibers 1 and output optical fibers 8 can also be controlled using the same procedure. As a specific circuit of the vibration frequency control circuit 9, a selector corresponding to l1m is provided for each vibrator 6.7,
It is connected to each vibrator 6.7 by individual wiring indicated by dotted lines in FIG.

(Effects of the Invention) As explained above, according to the present invention, it is possible to switch a large number of input/output signals with a single-stage switching mechanism.
Unlike conventional optical switches in which two-manufactured, two-output switches are connected in multiple stages to switch a large number of input and output signals, optical signals can be switched without accumulating H4 loss or crosstalk as the number of inputs and outputs increases. Since switching can be performed, there is an advantage that a large-scale optical switch can be constructed.

Furthermore, since it is possible to connect one input to a plurality of outputs and to connect a plurality of inputs to one output, there is an advantage that switching of optical signals that involves signal branching and combining processing can be performed.

[Brief explanation of drawings]

Figure 1 is a connection layout diagram showing an example of the configuration of a conventional optical switch.
FIG. 2 is a layout diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a configuration example of a vibration frequency control circuit used in the present invention. ■...Input optical fiber, 2...Lens, 3...
- Lens, 4... Acousto-optic element, 5... Acousto-optic element, 6... Vibrator, 7... Vibrator, 8...
Output optical fiber, 9... vibration frequency control circuit, 10-1.10-2. −． 10-N...oscillator, 11
m...Selector.

Claims (1)

[Claims] a first lens that converts light emitted from an input optical fiber into a parallel beam; a second lens that efficiently couples the parallel beam to an output optical fiber; a first acousto-optic element through which the beam passes;
a second acousto-optic element that is disposed close to the second lens and through which the parallel beam that has passed through the first acousto-optic element passes; An optical switch comprising a vibrator that generates electricity and a circuit that controls the vibration frequency of the vibrator.