Abstract: An optical receiver module which receives a first optical signal including a continuous signal or a burst signal includes: a variable optical attenuator which adjusts the first optical signal to output a second optical signal; a semiconductor optical amplifier which amplifies the second optical signal to output a third optical signal; and a controller which controls an output of at least one of the variable optical attenuator and the semiconductor optical amplifier so as to cause the semiconductor optical amplifier to operate in a region in which gain saturation of the semiconductor optical amplifier does not occur, on the basis of at least one of: a power obtained by suppressing an outside portion of the wavelength band of the first optical signal in the third optical signal; and a power obtained by extracting the outside portion of the wavelength band of the first optical signal in the third optical signal.

Abstract: A PON system according to one manner of the present invention includes an optical line terminal (OLT), at least one optical network unit (ONU), and an optical fiber that connects the optical line terminal and the optical network unit to each other. A reception level category for categorizing a reception level in the optical network unit, of an optical signal sent from the optical line terminal through the optical fiber is set. In discovery processing for searching for and registering an unregistered optical network unit, the optical line terminal registers an optical network unit corresponding to the reception level category.

Abstract: An optical signal repeater includes: at least one first repeating unit configured to repeat an optical signal; at least one second repeating unit configured to be interchangeable with the first repeating unit; a branch portion configured to branch an optical signal and provide the branched optical signal to each of the first repeating unit and the second repeating unit; a failure determination unit configured to compare a signal output from the first repeating unit with a signal output from the second repeating unit, and determine presence or absence of failure in the first repeating unit; and a redundancy switching control unit configured to, if the failure determination unit determines the presence of failure in the first repeating unit, execute redundancy switching between the first repeating unit and the second repeating unit.

Abstract: A PON system according to one manner of the present invention includes an optical line terminal (OLT), at least one optical network unit (ONU), and an optical fiber that connects the optical line terminal and the optical network unit to each other. A reception level category for categorizing a reception level in the optical network unit, of an optical signal sent from the optical line terminal through the optical fiber is set. In discovery processing for searching for and registering an unregistered optical network unit, the optical line terminal registers an optical network unit corresponding to the reception level category.

Abstract: A host board for mounting an optical transceiver includes a connector that is configured to attach thereto and detach therefrom an optical transceiver having at least one lane and includes electrical contacts as many as the at least one lane, a management unit configured to receive lane information regarding the at least one lane of the optical transceiver from the optical transceiver through the connector and specify an available electrical contact, and a communication unit configured to communicate with the optical transceiver through the connector. The communication unit is configured to communicate information with the optical transceiver through the electrical contact specified by the management unit.

Abstract: An optical receiver module which receives a first optical signal including a continuous signal or a burst signal includes: a variable optical attenuator which adjusts the first optical signal to output a second optical signal; a semiconductor optical amplifier which amplifies the second optical signal to output a third optical signal; and a controller which controls an output of at least one of the variable optical attenuator and the semiconductor optical amplifier so as to cause the semiconductor optical amplifier to operate in a region in which gain saturation of the semiconductor optical amplifier does not occur, on the basis of at least one of: a power obtained by suppressing an outside portion of the wavelength band of the first optical signal in the third optical signal; and a power obtained by extracting the outside portion of the wavelength band of the first optical signal in the third optical signal.

Abstract: A pluggable optical module includes: a circuit board insertable to and removable from a connector of a host board; a plurality of first electrodes arranged in a first direction, which crosses an insert direction of the pluggable optical module, on a first surface of the circuit board; and a plurality of second electrodes arranged in the first direction on the first surface of the circuit board, the second electrodes being arranged on a host board side associated with the host board, with respect to the plurality of first electrodes. The first and second electrodes are arranged in accordance with a layout rule for tolerating electrical impact occurring when at least one of a plurality of terminals of the connector configured to be brought into contact with respective first electrodes of the plurality of first electrodes contacts any electrode of the plurality of second electrodes.

Abstract: An optical transmitter includes a plurality of light-emitting units each configured to transmit an optical signal having a different wavelength and change the wavelength of the optical signal. At least one light-emitting unit of the plurality of light-emitting units is configured to adjust the wavelength.

Abstract: A host board for mounting an optical transceiver includes a connector that is configured to attach thereto and detach therefrom an optical transceiver having at least one lane and includes electrical contacts as many as the at least one lane, a management unit configured to receive lane information regarding the at least one lane of the optical transceiver from the optical transceiver through the connector and specify an available electrical contact, and a communication unit configured to communicate with the optical transceiver through the connector. The communication unit is configured to communicate information with the optical transceiver through the electrical contact specified by the management unit.

Abstract: A configuration for receiving transmission data at multiple rates where one rate is not necessarily a multiple of another is provided. A host board includes a receiving circuit, a cross point switch, and a switch control circuit. The receiving circuit includes a receiving unit configured to receive a first data signal transmitted at a first rate, and a second receiving unit configured to receive a second data signal transmitted at a second rate different from the first rate. The cross point switch includes input terminals and output terminals. The cross point switch is configured to define a path of signal between the input terminals and the output terminals to route an input data signal to at least one of the first receiving unit and the second receiving unit.

Abstract: A configuration for receiving transmission data at multiple rates where one rate is not necessarily a multiple of another is provided. A host board includes a receiving circuit, a cross point switch, and a switch control circuit. The receiving circuit includes a receiving unit configured to receive a first data signal transmitted at a first rate, and a second receiving unit configured to receive a second data signal transmitted at a second rate different from the first rate. The cross point switch includes input terminals and output terminals. The cross point switch is configured to define a path of signal between the input terminals and the output terminals to route an input data signal to at least one of the first receiving unit and the second receiving unit.

Abstract: An optical branching/synthesizing device 20A includes an optical branching coupler group 25A and an optical combiner 26. The optical branching coupler group 25A includes a first-stage optical branching coupler 22 that receives a downstream optical signal Sd from an OLT device 12 at light input/output end 22a, and second-stage optical branching couplers 23 and 24 including light input/output ends 23b and 24a connected to light input/output ends 22c and 22d of the optical branching coupler 22 at the previous stage, respectively. A light input/output ends 23a, 23b, 24a, 24b of the optical branching couplers 23 and 24 transmit the downstream optical signal Sd to each ONU device 13 and receive upstream optical signals Su from the ONU devices 13. The optical combiner combines the upstream optical signals Su output from the light input/output ends 22b, 23a, and 24b of the optical branching couplers 22 to 24.

Abstract: An optical branching/synthesizing device 20A includes an optical branching coupler group 25A and an optical combiner 26. The optical branching coupler group 25A includes a first-stage optical branching coupler 22 that receives a downstream optical signal Sd from an OLT device 12 at light input/output end 22a, and second-stage optical branching couplers 23 and 24 including light input/output ends 23b and 24a connected to light input/output ends 22c and 22d of the optical branching coupler 22 at the previous stage, respectively. A light input/output ends 23a, 23b, 24a, 24b of the optical branching couplers 23 and 24 transmit the downstream optical signal Sd to each ONU device 13 and receive upstream optical signals Su from the ONU devices 13. The optical combiner combines the upstream optical signals Su output from the light input/output ends 22b, 23a, and 24b of the optical branching couplers 22 to 24.

Abstract: An optical transmitter with a plurality of transmitter units each providing a Peltier device is disclosed. The Peltier devices of the invention are connected in series with respect to the driver, accordingly, even when the Peltier devices show a relative low impedance, a total load impedance viewed from the driver becomes a substantial value and the total power consumption of the transmitter may be reduced.

Abstract: The present invention reduces the radiation noise and the degradation of the optical waveform appeared in the output of the laser module. The laser module of the present invention comprises the laser diode, the photodiode, and the resistor, which are mounted on the stem of the laser module. The stem includes four lead terminals, one of which is commonly connected to the laser diode ad the photodiode via the resistor. Therefore, the leak of the modulation current applied to the lead terminal, to which the laser diode and the photodiode are commonly connected, may be reduced.

Abstract: In a semiconductor laser manufacturing method, a GaN single-crystal substrate is formed by slicing a GaN bulk crystal, grown on a c-plane, parallel to an a-plane which is perpendicular to the c-plane. In this substrate, crystal defects extending parallel to the c-axis direction do not readily exert an influence, and degradation of element characteristics due to crystal defects can be suppressed. Further, because the a-plane is a nonpolar plane, improved light emission efficiency and longer wavelengths can be achieved compared with the c-plane, which is a polar plane. Hence a semiconductor laser manufacturing method of this invention enables further improvement of the element characteristics of the semiconductor laser to be fabricated.

Abstract: The present invention is to provide an intelligent pluggable transceiver improving an EMI tolerance with a simple mechanism. The optical transceiver of the invention comprises upper and lower housings (11, 12), a holder (81), optical assemblies (51, 61), a cover (14), a substrate (15) and a grip (13). The optical assemblies are fixed with the upper and lower housings together with the holder with interposing the conductive elastic member. Although the rear end of the substrate exposes outside the transceiver, the shield gasket and the ground pattern on the substrate shields the contact portion between the substrate and the upper housing and between the substrate and the cover. Moreover, the grip and the latch lever installed in the lower housing, and the elastic piece realize the latching/releasing mechanism of the transceiver with the host system.

Abstract: The present invention is to provide an intelligent pluggable transceiver improving an EMI tolerance with a simple mechanism. The optical transceiver of the invention comprises upper and lower housings (11, 12), a holder (81), optical assemblies (51, 61), a cover (14), a substrate (15) and a grip (13). The optical assemblies are fixed with the upper and lower housings together with the holder with interposing the conductive elastic member. Although the rear end of the substrate exposes outside the transceiver, the shield gasket and the ground pattern on the substrate shields the contact portion between the substrate and the upper housing and between the substrate and the cover. Moreover, the grip and the latch lever installed in the lower housing, and the elastic piece realize the latching/releasing mechanism of the transceiver with the host system.

Abstract: The present invention is to provide an optical transceiver that enhances and keeps the exactness of the transmission rate of the optical signal to be transmitted. The transceiver includes a rate adjustor, where the de-stuffing unit, the FIFO memory and the stuffing unit. The input electrical data are temporarily stored in FIFO memory synchronized with the clock extracted from the input data. The stored data are read out by the clock highly stabilized by the voltage controlled oscillator (VCO). The control signal for the VCO is compensated to the temperature.

Abstract: The present invention is to provide a laser module that includes a semiconductor laser diode that is raised in a temperature without degrading the heat dissipating efficiency to improve the operation and the performance of the laser diode. The laser module of the invention, having a co-axial package, includes a laser diode, and a heat sink on which the laser diode is mounted. The heat sink also provides a heater on a surface thereof. Supplying a heater current to the heater, the laser diode is raised in a temperature, which improves the operation on the laser diode at a lower ambient temperature.