Abstract: A repeater includes a variable optical attenuating unit that collectively attenuates WDM optical signal input, an optical-attenuation adjusting unit that adjusts attenuation in the variable optical attenuating unit, and an optical amplifying unit that collectively amplifies and outputs the WDM optical signal collectively attenuated, to a downstream side. An optical-attenuation adjusting unit includes an input level detector; an output level detector; an output-level transmitting unit that receives information of a signal level of WDM optical signal output by a repeater at an upstream side and transmits information of a signal level of the WDM optical signal detected by the output level detector to a repeater at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount thereof based on information of a signal level detected by the input level detector and a signal level received by the output-level transmitting unit.

Abstract: A repeater includes a variable optical attenuating unit that collectively attenuates WDM optical signal input, an optical-attenuation adjusting unit that adjusts attenuation in the variable optical attenuating unit, and an optical amplifying unit that collectively amplifies and outputs the WDM optical signal collectively attenuated, to a downstream side. An optical-attenuation adjusting unit includes an input level detector; an output level detector; an output-level transmitting unit that receives information of a signal level of WDM optical signal output by a repeater at an upstream side and transmits information of a signal level of the WDM optical signal detected by the output level detector to a repeater at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount thereof based on information of a signal level detected by the input level detector and a signal level received by the output-level transmitting unit.

Abstract: A multiplexer includes an encoder. The encoder includes: flip-flop circuits that output two signals having a transmission rate of B/2 at a frequency of B/2, while holding signals of each signal; an adder that adds the respective signals output from the flip-flop circuits and outputs the added signal; and a delay unit that delays the signal output from the flip-flop circuit by the time of 1/B, with respect to the signal output from the flip-flop circuit, and outputs the signal delayed to the adder.

Abstract: The optical amplifier according to the present invention is constructed such that the amount of the electric current fed to the power feeding line 2a is first detected by the current detection means, and then a setting signal is generated to each of the bypass circuits 22 and 23 in accordance with the thus detected amount of the fed current, and thereafter the output level of each of the optical repeater circuits 11 and 12 is controlled respectively by the bypass circuits 22 and 23, so that the output level of these repeater circuits 11 and 12 can be controlled in accordance with the amount of the current fed to the power feeding line 2a.

Abstract: The present invention has an object to obtain an optical signal quality supervisory device that supervises the quality of an optical signal simply, efficiently and with high accuracy without inviting an increase in cost, an increase in circuit scale and increase in power consumption. The bit rate of the optical supervisory channel is made lower than the bit rate of the optical main channel that is transmitted over an optical communication system, but the reception electric band width of a receiver that receives the optical supervisory channel is made equal to or wider than the reception electric band width of a receiver that receives the optical main channel. Also, the optical supervisory channel is made up of an SOH (section over head) frame to detect an error of the BIP (bit interleaved parity) byte of SOH, thereby supervising the quality of the optical communication system, in particular, the light wave network.

Abstract: A multiplexer includes an encoder (4). The encoder (4) includes: flip-flop circuits (4a, 4b) that output two signals having a transmission rate of B/2 at a frequency of B/2, while holding signals of each signal; an adder (4f) that adds the respective signals output from the flip-flop circuits (4a, 4b) and outputs the added signal; and a delay unit (4e) that delays the signal output from the flip-flop circuit (4b) by the time of 1/B, with respect to the signal output from the flip-flop circuit (4a), and outputs the signal delayed to the adder (4f).

Abstract: An optical-electrical (OE) conversion unit (11) converts optical signals received through an optical transmission line into first electrical signals and second electrical signals. A multilevel identification unit (12) identifies the first electrical signals based on a plurality of identification levels, and produces multinary identification signals. A serial-parallel conversion circuit (13) converts the multinary identification signals into multinary parallel signals. An optical reception quality circuit (14) produces reliability information that indicates quality of optical signals from the second electrical signals. An error-correction decoding circuit (15) corrects errors based on the multinary parallel signals and the reliability information, and outputs error-corrected parallel signals.

Abstract: The optical amplifier according to the present invention is constructed such that the amount of the electric current fed to the power feeding line 2a is first detected by the current detection means, and then a setting signal is generated to each of the bypass circuits 22 and 23 in accordance with the thus detected amount of the fed current, and thereafter the output level of each of the optical repeater circuits 11 and 12 is controlled respectively by the bypass circuits 22 and 23, so that the output level of these repeater circuits 11 and 12 can be controlled in accordance with the amount of the current fed to the power feeding line 2a.

Abstract: The optical amplifier according to the present invention is constructed such that the amount of the electric current fed to the power feeding line 2a is first detected by the current detection means, and then a setting signal is generated to each of the bypass circuits 22 and 23 in accordance with the thus detected amount of the fed current, and thereafter the output level of each of the optical repeater circuits 11 and 12 is controlled respectively by the bypass circuits 22 and 23, so that the output level of these repeater circuits 11 and 12 can be controlled in accordance with the amount of the current fed to the power feeding line 2a.

Abstract: An optical switch includes a polymer optical waveguide that is a plate material basically made of polymer and a drive element. The plate material has optical waveguides that extend linearly within the plate material and a cut provided such that it traverses the optical waveguides. The drive element selects a path of light by reducing and increasing a gap of the cut.

Abstract: An optical switching system is implemented by providing a transmitting section with a preparatory transmitted optical signal selector and a working transmitted optical signal splitter, which are each implemented by a 1×2 optical space switch, and by providing a receiving section with a receiving optical switch which is implemented by a 2×2 optical space switch, and with a preparatory receiving optical gate which is implemented by a 1×2 optical space switch. This makes it possible to switch between the working system and preparatory system without employing any 4×4 optical space switch, thereby implementing a practical optical switching system without causing such problems as communication interruption during maintenance or impairment of transmission path working efficiency.

Abstract: An optical switch includes a polymer optical waveguide that is a plate material basically made of polymer and a drive element. The plate material has optical waveguides that extend linearly within the plate material and a cut provided such that it traverses the optical waveguides. The drive element selects a path of light by reducing and increasing a gap of the cut.

Abstract: An optical switch includes a light emitter for emitting light and light receivers. A reflector is used for changing a path of light emitted from the light emitter. The reflector is held by a permanent magnet having first and second magnetic poles of opposite polarities. A supporting member is provided for the reflector and the first permanent magnet so that the reflector and the first permanent magnet can move between a first position and a second position. In the first position, the reflector and the first permanent magnet interact so the emitted light travels into one light receiver of the light receivers. On the other hand, in the second position, the reflector and the first permanent magnet interact so the emitted light travels into another of the light receivers. The switch further includes an electromagnet for generating first and second magnetic fields selectively for moving the reflector and the first permanent magnet between the first and second positions.

Abstract: When an intensity modulating operation and a phase modulating operation are carried out by employing a 2-electrode MachZehnder type optical modulator preferably a LN-MZ type optical modulator, a drive signal of this 2-electrode LN-MZ type optical modulator is produced from an intensity modulation signal and a phase modulation signal with a low loss and a simple arrangement.

Abstract: An optical communication system comprising a plurality of optical signal communication paths, and a plurality of terminals coupled to the plurality of communication paths. A connection request is made by a calling terminal to a called terminal with an optical signal at a control wavelength via the communication path. A wavelength control unit monitors the communication paths and in response to the connection request signal selects an optical signal wavelength to be used by the terminals, out of any unused wavelengths on the communication paths. Further, the wavelength control unit informs the calling and called terminals of the selected wavelength via a wavelength information optical signal at the control wavelength. The calling and called terminals, responsive to the wavelength information signal, set their transmitting and receiving wavelength to the selected unused wavelength.