JPS6143690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical pulse delay circuit. A conventional optical pulse delay circuit is constructed by combining an optical branching circuit, an optical multiplexing circuit, and a plurality of delay fibers of different lengths. but,
In the conventional method, multiple delay optical fibers are required to obtain different delay times, and alignment of these multiple delay optical fibers with the optical branching circuit and the optical multiplexing circuit is complicated. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical delay circuit which eliminates the above-mentioned drawbacks, allows different delay times to be obtained just by using a single delay optical fiber, and which simplifies alignment.

According to the present invention, a direction switching optical switch circuit, an electrical means for driving the optical switch circuit, and a delay low-loss optical fiber are provided, and both ends of the delay low-loss optical fiber are connected to each other as if forming a closed loop. Connect one set of input/output terminals of the optical switch circuit for switching, and connect the optical fiber for optical signal input/output to the other set of input/output terminals of the optical switch circuit for direction switching. By driving,
An optical delay circuit is obtained, which is characterized in that two sets of optical pulse trains output to an optical fiber for optical signals and a low-loss optical fiber for delay can be exchanged.

The advantage of the present invention is that the total time of propagation through the low-loss optical fiber for delay and the optical switch circuit for direction switching is defined as one cycle, and a delay time of any integral multiple of this cycle is given to the optical signal output. This is something that can be done.

Further, according to the present invention, there is an advantage that the temporal order of the optical pulse train can be easily changed.

Next, the present invention will be explained in detail with reference to the drawings. The figure is a configuration diagram showing an embodiment of the optical delay circuit of the present invention.

In the figure, 1 is a direction switching optical switch circuit;
2 is a driving circuit for this optical switch circuit. This drive circuit is capable of controlling the operation mode of the direction switching optical switch circuit by an external timing signal. This direction switching optical switch circuit can be constructed by using, for example, a stripe guide type coupling modulator that utilizes electro-optic effects. Reference numeral 3 denotes a delay low-loss optical fiber, and both ends of this optical fiber are connected to a set of input/output terminals of the direction switching optical switch circuit 1 in such a manner that optical coupling loss is reduced as much as possible. 4 is a fiber for optical signal input, and 5 is a fiber for optical signal output. 4 and 5 are connected to the other set of input/output terminals of the direction switching optical switch circuit 1, respectively. The direction switching optical switch circuit 1 has two operation modes, and outputs the optical input signals from the corresponding optical fibers connected to the two input terminals of the direction switching optical switch circuit 1 to the two corresponding output terminals. There is a parallel propagation mode in which the optical signals propagate as they are, and an exchange propagation mode in which the optical input signals from two optical fibers are exchanged and transmitted to different output terminals. Mode can be selected.
To give a delay to the optical pulse, first, the optical signal input fiber 4 is excited, and at the same time, a timing signal is applied to the drive circuit 2, and the optical input signal is guided to the delay loss optical fiber 3. In this way, one of the delay circuits
The optical signal pulse train included within the period can be taken into the delay loss optical fiber 3. When the direction switching optical switch circuit 1 is set to the parallel mode with the optical pulse train entering the optical fiber 3, the optical pulse train taken into the delay low-loss optical fiber 3 goes around in a closed loop and is stored for a long time.
If the direction switching optical switch circuit 1, the low-loss fiber 3, and their connections are made to have low loss, attenuation will be reduced, making it easier to obtain a long delay. When the direction switching optical switch circuit 1 is set to exchange mode after the required period has elapsed, the optical pulse signal temporarily stored in the delay low-loss optical fiber 3 is guided to the optical signal output fiber 5. It then propagates to the outside.

By using this optical delay circuit, the temporal order of two different optical pulse trains excited in the optical signal input fiber 4 can be switched. First, the first optical pulse train is taken into the delay low-loss optical fiber 3, and then the next pulse train is guided into the optical signal output fiber 5 in the parallel propagation mode of the direction switching optical switch circuit, and then an appropriate optical pulse train is introduced into the optical signal output fiber 5. After some time,
The purpose is achieved by converting the optical pulse train stored in the direction switching optical switch circuit into an exchange propagation mode and guiding it to the optical signal output fiber 5.

If the length of the delay optical fiber 3 is made long, a long optical pulse train can be taken in, which is convenient depending on the application.

If a problem arises where the attenuation of the delayed optical pulse becomes too large due to a delay of an integer multiple of the period, inserting an amplifier etc. in the middle of the low loss fiber for delay in step 3 will reduce the output. The optical pulse can be restored.

As described above, according to the present invention, by using one delay optical fiber, different time delays can be obtained, and a simple and useful optical delay circuit that requires few alignments can be obtained.

[Brief explanation of the drawing]

The figure shows an example of the configuration of an optical delay circuit which is an embodiment of the present invention, in which 1 is an optical switch circuit for switching, 2 is an electric circuit for driving the optical switch circuit, 3 is a low-loss optical fiber for delay, and 4 is a low-loss optical fiber for delay. An optical fiber for optical signal input, 5 is a fiber for optical signal output.

Claims (1)

[Claims] 1. A direction switching optical switch circuit having a plurality of sets of input/output terminals, a delay optical fiber connected to the set of input terminals to form a closed loop, and a set of other input/output terminals of the direction switching optical switch. Optical signal input and output optical fibers are connected to the optical switch circuit, and the propagation direction of light in the optical switch circuit is changed from the input optical fiber to the delay optical fiber, or from the delay optical fiber to the output optical fiber. 1. An optical delay circuit comprising a driving means for switching to a fiber, and capable of confining and delaying the delaying optical fiber optical signal for an arbitrary period of time according to a control signal of the driving means.