Abstract: There is provided a wavelength division multiplex transmission system with satisfactory transmission characteristics and extensive functions for avoidance of defects. Transmission signals to be transmitted by an optical transmission device are distributed among a plurality of wavelength components, converted into WDM signals, and sent to a WDM transmission network, and WDM signals from the WDM transmission network are restored to the transmission signals by an optical receiving device. This system includes a wavelength component-specific route setting device which sets routes for transmission on the WDM transmission network for each wavelength component.

Abstract: An optical communication network using a communication system which is combined optical time-division multiplexing and optical wavelength-division multiplexing. The electric/optical converter converts an electric signal strings, which are input from the outside, into optical burst signals by selectively using a plurality of types of optical wavelengths. The network controller controls the optical wavelength selected by the electric/optical converter and the output timing of the optical burst signals for each one of the optical burst signals so that the optical burst signals received by the OLT are time-division multiplexed and wavelength-division multiplexed. By combining optical time-division multiplexing and optical wavelength-division multiplexing, an optical communication network of which the transmission band is wider than a TDMA system can be provided with a lower cost and lower facility scale than a WDM system.

Abstract: An optical transmission system according to the present invention includes a connection confirming circuit 106 for confirming connection of an input data signal, a test signal generator 105 for generating a test signal, and a switching device 107 on a transmitter side. The switching device 107 selectively generates the input data signal from an output terminal in the case where the input data signal is detected by the connection confirming circuit 106, and the test signal when the input data signal is not detected. An output of the switching device 107 is connected to an optical transmitter TX. On a receiver side, there is provided a determination circuit for receiving an optical signal from a transmission path and detecting the test signal to determine transmission characteristics of the transmission path on the basis of the test signal.

Abstract: Each optical repeater in an optical transmission system includes an optical amplifier, and a control circuit for controlling the optical transmission. Furthermore, each optical repeater transmits management information to the next optical repeater. The control circuit checks the status of the optical amplifier and obtains monitoring information. The control circuit generates management information in accordance with the monitoring information and the management information transmitted from the upstream side optical repeater. The management information is converted to an optical signal and transmitted to the next optical repeater. A receiving station receives the management information. The management information includes an ID code for an optical repeater which has failed and the status of the failure.

Abstract: A high-voltage generating circuit suitable for a light receiving circuit includes a pulse oscillating circuit, a current drive circuit, a first capacitor, a second capacitor, a Cockcroft-Walton circuit, a low-pass filter. The pulse oscillating circuit produces a train of repetitive pulses. The current drive circuit produces a train of repetitive pulses which are in phase opposite to the train of repetitive pulses. The first capacitor couples the current drive circuit with the first input terminal of the Cockcroft-Walton circuit. The second capacitor couples the pulse oscillating circuit with the second input terminal of the Cockcroft-Walton circuit. The Cockcroft-Walton circuit boost the pulse voltage applied between the first and second inputs to produce a high direct current voltage. The low-pass filter removes the ripple components of the high direct current voltage. The Cockcroft-Walton circuit can be formed with a small number of circuit components.

Abstract: In a variable high-voltage generating circuit for an avalanche photodiode, a pulse oscillating circuit generates pulses, a current driving circuit current-amplifies the pulses, a Cockcroft-Walton circuit boosts and rectifies the pulses from the current driving circuit, and a low-pass filter is connected at the output of the Cockcroft-Walton circuit. The avalanche photodiode is connected in series with a first resistor, and the series connection is connected to receive the output of the low-pass filter. A series connection of a transistor and a second resistor is connected in parallel with the series connection of the avalanche diode and the first resistor. A control circuit applies a variable signal to the base of the transistor, thereby to vary the voltage applied across the APD.