Abstract: An optical transmitter device includes a modulator of the Mach-Zehnder type that modulates the optical signal from an emitter and outputs modulated signals; and a phase controller that controls the phase difference of the modulator according to a setting phase amount. The device includes a controller, a sweeper, and an estimator. The controller controls the bias current of the emitter so that the power of the modulated signals detected at the output stage of the modulator during the optical shutdown becomes the target value during the optical shutdown. After the bias current is controlled, the sweeper performs constant-period sweeping of the phase of the modulator. The estimator estimates, while sweeping the phase, the transmission characteristics of the modulator from the power of the optical signal detected at the input stage of the modulator; and, from the estimated characteristics, calculates the optimum phase amount to be set in the phase controller.

Abstract: An optical transmission device includes a first detector, a generator, a second detector, and a controller. The first detector detects optical output power of an optical signal for each channel for input to a Mach-Zehnder unit that has asymmetric optical waveguides. The generator superimposes, based on the detected optical output power for each of the channels, a dither signal onto an optical signal in a specific channel from among the plurality of channels for input to the Mach-Zehnder unit. The second detector detects an amplitude value of the dither signal superimposed onto the optical signal in the specific channel output from the Mach-Zehnder unit. The controller adjusts a phase difference in the Mach-Zehnder unit such that the amplitude value of the dither signal superimposed onto the detected optical signal in the specific channel is less than a predetermined threshold.

Abstract: An optical transmission device includes a first detector, a generator, a second detector, and a controller. The first detector detects optical output power of an optical signal for each channel for input to a Mach-Zehnder unit that has asymmetric optical waveguides. The generator superimposes, based on the detected optical output power for each of the channels, a dither signal onto an optical signal in a specific channel from among the plurality of channels for input to the Mach-Zehnder unit. The second detector detects an amplitude value of the dither signal superimposed onto the optical signal in the specific channel output from the Mach-Zehnder unit. The controller adjusts a phase difference in the Mach-Zehnder unit such that the amplitude value of the dither signal superimposed onto the detected optical signal in the specific channel is less than a predetermined threshold.

Abstract: A power-saving mode flag generating unit 101e sets a power-saving mode flag to active (non power-saving mode, turning on the power-source) when it receives a reset signal from a MAC unit 102. Furthermore, the power-saving mode flag generating unit 101e sets the power-saving mode flag to sleep (power-saving mode, turning off the power source) in accordance with a signal-interrupt detection signal obtained by the signal-interrupt detecting unit 101f1 of the packet monitoring unit 101f. Depending on the state of a packet, the power-saving mode flag generating unit 101e changes the power-saving mode flag to active or sleep for the data communication area of the packet; however, for the ranging area of the packet, the power-saving mode flag generating unit 101e always sets the power-saving mode flag to active. A pattern discriminating unit 101g discriminates between the data communication area and the ranging area of the packet.

Abstract: A power-saving mode flag generating unit 101e sets a power-saving mode flag to active (non power-saving mode, turning on the power-source) when it receives a reset signal from a MAC unit 102. Furthermore, the power-saving mode flag generating unit 101e sets the power-saving mode flag to sleep (power-saving mode, turning off the power source) in accordance with a signal-interrupt detection signal obtained by the signal-interrupt detecting unit 101f1 of the packet monitoring unit 101f. Depending on the state of a packet, the power-saving mode flag generating unit 101e changes the power-saving mode flag to active or sleep for the data communication area of the packet; however, for the ranging area of the packet, the power-saving mode flag generating unit 101e always sets the power-saving mode flag to active. A pattern discriminating unit 101g discriminates between the data communication area and the ranging area of the packet.

Abstract: An optical receiver comprising: a photoelectric converting unit converting an input optical signal into an converted electrical signal; a splitting unit splitting the converted electrical signal into a plurality of split electrical signals; an amplifier amplifying one of the plurality of the split electrical signals with a first input time constant and thereby outputting an output signal; a detection circuit detecting an interruption of the input optical signal with a second input time constant on the basis of one of the plurality of the split electrical signals other than the one of the plurality of the split electrical signals input to the amplifier and thereby outputting a detection signal; and a delay circuit configured to delay the detection signal; wherein, the second input time constant of the detection circuit is smaller than the first input time constant of the amplifier.

Abstract: In an optical module in which a transmitter and a receiver that respectively outputs and receives optical signals are stored in a casing, the transmitter and the receiver are connected to a common power line and to a common ground line, and a ferrite bead is arranged on the ground line in the receiver. The ferrite bead absorbs a high-frequency current component out of components in an electric signal passing through the ground line on which the ferrite bead is arranged. An inductance component that evolves on a ground line and a power line of a light receiving element and oscillation of a series resonance circuit that is formed of a capacitance component of the light receiving element are suppressed to reduce crosstalk.

Abstract: An optical transmitting/receiving apparatus capable of suppressing electrical crosstalk and magnetic crosstalk, includes: a laser diode/photo diode (LD/PD) integrated module that terminates a single-core bidirectional optical fiber; a circuit board electrically connected to a lead pin led out of the LD/PD integrated module; and a plastic case that accommodates the circuit board. At least a part of the plastic case abuts against the LD/PD integrated module, and impedance of the plastic case is controlled by mixing a conductive filler into the plastic case.

Abstract: An optical transmitting/receiving apparatus capable of suppressing electrical crosstalk and magnetic crosstalk, includes: a laser diode/photo diode (LD/PD) integrated module that terminates a single-core bidirectional optical fiber; a circuit board electrically connected to a lead pin led out of the LD/PD integrated module; and a plastic case that accommodates the circuit board. At least a part of the plastic case abuts against the LD/PD integrated module, and impedance of the plastic case is controlled by mixing a conductive filler into the plastic case.

Abstract: An optical receiver comprising: a photoelectric converting unit converting an input optical signal into an converted electrical signal; a splitting unit splitting the converted electrical signal into a plurality of split electrical signals; an amplifier amplifying one of the plurality of the split electrical signals with a first input time constant and thereby outputting an output signal; a detection circuit detecting an interruption of the input optical signal with a second input time constant on the basis of one of the plurality of the split electrical signals other than the one of the plurality of the split electrical signals input to the amplifier and thereby outputting a detection signal; and a delay circuit configured to delay the detection signal; wherein, the second input time constant of the detection circuit is smaller than the first input time constant of the amplifier.

Abstract: An optical transmitting/receiving apparatus capable of suppressing electrical crosstalk and magnetic crosstalk, includes: a laser diode/photo diode (LD/PD) integrated module that terminates a single-core bidirectional optical fiber; a circuit board electrically connected to a lead pin led out of the LD/PD integrated module; and a plastic case that accommodates the circuit board. At least a part of the plastic case abuts against the LD/PD integrated module, and impedance of the plastic case is controlled by mixing a conductive filler into the plastic case.

Abstract: In an optical module in which a transmitter and a receiver that respectively outputs and receives optical signals are stored in a casing, the transmitter and the receiver are connected to a common power line and to a common ground line, and a ferrite bead is arranged on the ground line in the receiver. The ferrite bead absorbs a high-frequency current component out of components in an electric signal passing through the ground line on which the ferrite bead is arranged. An inductance component that evolves on a ground line and a power line of a light receiving element and oscillation of a series resonance circuit that is formed of a capacitance component of the light receiving element are suppressed to reduce crosstalk.

Abstract: An optical module includes a semiconductor package, a holder holding the semiconductor package, and a metal casing having a bottom surface, first and second confronting sidewalls, and third and fourth confronting sidewalls. The first sidewall has a pair of parallel edges defining a cutout extending to the bottom surface. The holder is accommodated within the metal casing on the bottom surface in a state where the metal casing is positioned by the pair of parallel edges, the third and fourth sidewalls and the bottom surface, so that the semiconductor package extends outside the metal casing via the cutout.

Abstract: An optical module includes a semiconductor package, a holder holding the semiconductor package, and a metal casing having a bottom surface, first and second confronting sidewalls, and third and fourth confronting sidewalls. The first sidewall has a pair of parallel edges defining a cutout extending to the bottom surface. The holder is accommodated within the metal casing on the bottom surface in a state where the metal casing is positioned by the pair of parallel edges, the third and fourth sidewalls and the bottom surface, so that the semiconductor package extends outside the metal casing via the cutout.

Abstract: Locating a fault of a transmission line in a system which performs bidirectional optical communication between a station-side device and plural subscriber devices and in which a transmission line 1 extending from the station-side device is branched by a branching/coupling device into plural transmission lines 2 each connected to the subscriber devices. The present invention provides a supervisory unit to the transmission line 1 and attenuators to respective transmission lines 2. The supervisory unit emits an optical test signal, observes a reflected signal of the test signal while changing the attenuation of the attenuators and locates the fault based on a return time and a return loss when the test signal returns as a reflected signal.