Abstract: An optical reception device includes: a light receiving element; an amplifier which receives and amplifies a current based on an input current from the light receiving element; a direct-current adjustment circuit which removes an offset current included in the input current; an alternating-current adjustment circuit which causes a part of the input current to flow therein; and a controller which controls the direct-current adjustment circuit and the alternating-current adjustment circuit. The controller includes an integrator configured to integrate an output of the amplifier and output a resultant output to two electric paths of a positive phase and a negative phase, and an inversion suppression circuit configured to operate so as to inject a current to the positive phase and extract a current from the negative phase when a negative phase potential of an output of the integrator is higher than a positive phase potential thereof.

Abstract: An optical reception device includes: a light receiving element; an amplifier which receives and amplifies a current based on an input current from the light receiving element; a direct-current adjustment circuit which removes an offset current included in the input current; an alternating-current adjustment circuit which causes a part of the input current to flow therein; and a controller which controls the direct-current adjustment circuit and the alternating-current adjustment circuit. The controller includes an integrator configured to integrate an output of the amplifier and output a resultant output to two electric paths of a positive phase and a negative phase, and an inversion suppression circuit configured to operate so as to inject a current to the positive phase and extract a current from the negative phase when a negative phase potential of an output of the integrator is higher than a positive phase potential thereof.

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: 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 signal repeater includes a separation unit that separates the plurality of optical signals according to wavelengths, a first clock data recovery (CDR) circuit configured to extract a first clock included in a first optical signal of the plurality of optical signals and having a first frequency corresponding to a first rate of the plurality of bit rates, a second CDR circuit configured to extract a second clock included in a second optical signal of the plurality of optical signals and having a second frequency corresponding to a second rate of the plurality of bit rates, a synchronous circuit that is synchronized with the first clock when the first clock is generated and is synchronized with the second clock when the first clock is not generated and the second clock is generated, and a control unit that controls the synchronous circuit.

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 receiver includes a light reception element for receiving an optical signal, a bias voltage supply/monitoring circuit for supplying a bias voltage to the light reception element and generating a monitoring voltage indicating magnitude of an output current of the light reception element, and a constant current source. The bias voltage supply/monitoring circuit is supplied with a remaining current obtained by subtracting the output current of the light reception element from an output current of the constant current source. The bias voltage supply/monitoring circuit converts the remaining current to the monitoring voltage.

Abstract: An optical communication module includes a modulation current supply circuit for supplying to a light-emitting element for transmitting a burst optical signal, a modulation current having magnitude in accordance with a logical value of data to be transmitted, a light-receiving element for monitoring, for outputting a current in accordance with intensity of light received from the light-emitting element, a measurement unit for measuring an output current from the light-receiving element for monitoring at set measurement timing, an adjustment unit for adjusting magnitude of the modulation current based on a result of measurement of the output current by the measurement unit, and a measurement timing setting unit for setting measurement timing based on a control signal for controlling transmission of the burst optical signal.

Abstract: An optical communication module includes a modulation current supply circuit for supplying to a light-emitting element for transmitting a burst optical signal, a modulation current having magnitude in accordance with a logical value of data to be transmitted, a light-receiving element for monitoring, for outputting a current in accordance with intensity of light received from the light-emitting element, a measurement unit for measuring an output current from the light-receiving element for monitoring at set measurement timing, an adjustment unit for adjusting magnitude of the modulation current based on a result of measurement of the output current by the measurement unit, and a measurement timing setting unit for setting measurement timing based on a control signal for controlling transmission of the burst optical signal.

Abstract: In the present invention, wasted power consumption caused when a clock and data recovery unit in an optical network unit in a PON system is activated from a power-saving state is reduced and rapid, secure communication is performed. A clock and data recovery unit includes a phase-locked loop that can be set to normal mode or power-saving mode and that includes a voltage-controlled oscillator and recovers a clock signal and a data signal from input signals. The clock and data recovery unit includes a reference clock multiplier circuit that multiplies a reference clock signal and outputs the multiplied reference clock signal; and a frequency training loop that includes the same voltage-controlled oscillator and performs synchronous oscillation training by the voltage-controlled oscillator using the reference clock multiplier circuit before the phase-locked loop transitions from power-saving mode to normal mode.

Abstract: A receiving unit using a voltage-controlled oscillator is allowed to compensate for the frequency characteristics of the voltage-controlled oscillator resulting from temperature change, without adding a capacitive element for temperature compensation. A receiving unit and an optical line terminal include a clock and data recovery circuit that extracts a clock signal and a data signal from a received signal, and have: a calibrator that calibrates an oscillation frequency of a voltage-controlled oscillator included in the clock and data recovery circuit; and a managing unit having a function of managing a schedule for receiving signals, the managing unit selecting a time where a duration of a certain state meets a time required for calibration by the calibrator to thereby output a reset signal (calibration instruction signal) to the calibrator, the state having no received signal (upstream signal) from which a clock signal and a data signal are to be extracted.

Abstract: An optical receiver includes a light reception element for receiving an optical signal, a bias voltage supply/monitoring circuit for supplying a bias voltage to the light reception element and generating a monitoring voltage indicating magnitude of an output current of the light reception element, and a constant current source. The bias voltage supply/monitoring circuit is supplied with a remaining current obtained by subtracting the output current of the light reception element from an output current of the constant current source. The bias voltage supply/monitoring circuit converts the remaining current to the monitoring voltage.

Abstract: In the present invention, wasted power consumption caused when a clock and data recovery unit in an optical network unit in a PON system is activated from a power-saving state is reduced and rapid, secure communication is performed. A clock and data recovery unit includes a phase-locked loop that can be set to normal mode or power-saving mode and that includes a voltage-controlled oscillator and recovers a clock signal and a data signal from input signals. The clock and data recovery unit includes a reference clock multiplier circuit that multiplies a reference clock signal and outputs the multiplied reference clock signal; and a frequency training loop that includes the same voltage-controlled oscillator and performs synchronous oscillation training by the voltage-controlled oscillator using the reference clock multiplier circuit before the phase-locked loop transitions from power-saving mode to normal mode.

Abstract: In the present invention, a receiving unit using a voltage-controlled oscillator, and the like are allowed to compensate for the frequency characteristics of the voltage-controlled oscillator resulting from temperature change, without adding a capacitive element for temperature compensation.