Abstract: An optical clock multiplier comprises a phase modulator (12) to shift a phase in pulse duration of an input optical clock pulse by &pgr;, a polarization mode dispersion device (16) having a predetermined time difference between first and second polarizations orthogonal to each other to divide an output light from the phase modulator into the first and second polarization components, and a polarization device (20) to extract one of polarization components in a third polarization practically inclined at an angle of 45° against the first polarization and a fourth polarization orthogonal to the third polarization out of the output light from the polarization mode dispersion device.

Abstract: An optical clock multiplier comprises a phase modulator (12) to shift a phase in pulse duration of an input optical clock pulse by &pgr;, a polarization mode dispersion device (16) having a predetermined time difference between first and second polarizations orthogonal to each other to divide an output light from the phase modulator into the first and second polarization components, and a polarization device (20) to extract one of polarization components in a third polarization practically inclined at an angle of 45° against the first polarization and a fourth polarization orthogonal to the third polarization out of the output light from the polarization mode dispersion device.

Abstract: To realize a highly reliable monitor control signal network at low costs, a data transmission system comprises a first network to optically transmit a data signal and a monitor control signal, first and second nodes connecting to the first network, and a second network capable of transmitting the monitor control signal.

Abstract: To improve the reliability of matrix switches of redundant configuration, a splitter (14) splits each of a plurality of input lights into two portions and applies them to corresponding input ports of matrix switches (10a and 10b). The working matrix switch (10a) connects between desired input and output ports and an optical shutter (30a) connecting to an output port (#1) is in a light transmission state. The matrix switch (10b) connects all its input ports (#1 through #8) to an output port (#1). An optical shutter (30b) connecting to an output port (#1) is in a light blocking state. A combiner (26) combines the lights which are output from the output ports (#1) of the matrix switches (10a and 10b) and transmitted through the optical shutters (30a and 30b) and also combines the output lights from the corresponding output ports (#2 through #8) of the matrix switches (10a and 10b).

Abstract: An optical reception apparatus comprises an optical receiver to receive an optical signal from an optical transmission line, an error corrector to correct an error of the signal received by the optical receiver and to transmit the error-corrected signal and error rate information before error correction, a judging apparatus to judge transmission quality of the optical transmission line according to the error rate information from the error corrector and a threshold value equal to an error rate lower than an error correction limit of the error corrector, and a selective breaker to transmit the signal whose error is corrected by the error corrector in normal state and to block transmission of the signal whose error is corrected by the error corrector when the judged result by the judging apparatus indicates deterioration of the transmission quality of the optical transmission line.

Abstract: An optical crossconnect system comprises an input stage including a plurality of input matrix switches, each having a plurality of input ports and a plurality of output ports, an output stage including a plurality of output matrix switches, each having a plurality of input ports and a plurality of output ports, and an intermediate stage including a plurality of intermediate matrix switches, each having a plurality of input ports and a plurality of output ports. Each input port of each intermediate matrix switch connects to an output port which corresponds to the intermediate matrix switch, at an input matrix switch corresponding to the input port in the plurality of input matrix switches. Each output port of each intermediate matrix switch connects to an input port, which corresponds to the intermediate matrix switch, at an output matrix switch corresponding to the output port in the plurality of output matrix switches.

Abstract: To improve the reliability of matrix switches of redundant configuration, a splitter (14) splits each of a plurality of input lights into two portions and applies them to corresponding input ports of matrix switches (10a and 10b). The working matrix switch (10a) connects between desired input and output ports and an optical shutter (30a) connecting to an output port (#1) is in a light transmission state. The matrix switch (10b) connects all its input ports (#1 through #8) to an output port (#1). An optical shutter (30b) connecting to an output port (#1) is in a light blocking state. A combiner (26) combines the lights which are output from the output ports (#1) of the matrix switches (10a and 10b) and transmitted through the optical shutters (30a and 30b) and also combines the output lights from the corresponding output ports (#2 through #8) of the matrix switches (10a and 10b).

Abstract: A drive motor control device for a video disk player or the like operates to brake the motor by driving it reversely upon reception of a rotation termination signal, until it is detected that the motor has stopped and rotates reversely. The motor is then driven forwardly for a predetermined time before being allowed to rotate freely to a stop.