Abstract: An optical transmitter transmits to an optical receiver a multi-carrier modulated signal light by driving a light source with a modulated signal modulated with a multi-carrier modulation scheme. The optical receiver monitors reception characteristic of any of subcarrier signals included in the modulated signal and transmits a monitor result to the optical transmitter. The optical transmitter controls drive conditions of the light source based on the monitor result received from the optical receiver.

Abstract: An optical reception apparatus may include a receiver, a monitor, and a controller. The optical reception apparatus receives multi-carrier modulated signal light modulated by a multi-carrier modulation scheme. The multi-carrier modulation scheme is available to allocate different transmission conditions for each of a plurality of subcarriers in accordance with transmission characteristics of the subcarriers. The receiver may receive from an optical transmission line a training signal light allocated with the same transmission conditions for each of the subcarriers. The monitor may monitor the transmission characteristics of the training signal light to detect a frequency at which a dip of the transmission characteristics occurs. The controller may control, based on the frequency detected by the monitor, a dispersion compensation for the multi-carrier modulated signal light having received a dispersion from the optical transmission line.

Abstract: An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.

Abstract: An apparatus includes a receiver configured to receive a signal that has traveled an optical transmission line without returning output from an optical transmitting device and synchronize with the optical transmitting device in order to demodulate the signal; a dispersion compensator configured to compensate for wavelength dispersion caused by transmission of the signal; an acquisition circuit configured to acquire a transmitting timing at which the signal has been transmitted from the optical transmitting device; a calculation circuit configured to calculate a transmission time period from the optical transmitting device to the receiver from the transmitting timing and a receiving timing at which the signal has been received with the receiver; and an amount setting circuit configured to adjust a dispersion compensation amount of the dispersion compensator in accordance with the transmission time period.

Abstract: A transmission apparatus including: a waveform shaper that performs spectrum correction on an optical signal converted from an electrical signal encoded by OFDM (Orthogonal Frequency Division Multiplexing); a converter that converts the optical signal on which the waveform shaper has performed the spectrum correction, into the electrical signal; and a nonlinear compensator that compensates for a nonlinear distortion with respect to the electrical signal converted by the converter.

Abstract: A heat sink including a base section, connection fins, and parallel fins. The base section includes: a first base plate configured to be mounted with a heat generating component on its outer surface; a second base plate disposed to face the first base plate in a parallel manner, configured to be mounted with a heat generating component on its outer surface; and a third base plate disposed perpendicular to the first base plate and the second base plate, which secures the first base plate and the second base plate along a junction line. The base section includes first and second regions arranged in the direction of the junction line. The connection fins are disposed on the first region to connect inner surfaces of the first and second base plates and to be parallel to the third base plate, and the parallel fins are disposed on the second region from an inner surface of the third base plate to be parallel to the first base plate.

Abstract: An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.

Abstract: An optical transmitter includes a discrete multi-tone (DMT) modulation unit that modulates a carrier signal having a specific frequency with an information signal and a carrier signal having a frequency different from the specific frequency with a monitor signal, to generate a DMT modulation signal that multiplexes the information signal and the monitor signal. The optical transmitter includes a laser diode (LD) unit that optically converts the DMT modulation signal to a corresponding optical DMT modulation signal, a frequency extraction unit that extracts a harmonic distortion component of the monitor signal from the optical DMT modulation signal, and a frequency analysis unit. The optical transmitter includes a bias control unit that controls a bias supply unit that adjusts a bias value to be supplied to the LD unit such that the extracted harmonic distortion component of the monitor signal is reduced.

Abstract: There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.

Abstract: Laminated ceramic capacitors include ceramic layers and inner electrodes that are alternately laminated. The inner electrodes are laminated in the same lamination direction, and a first outer electrode and a second outer electrode are electrically connected to the inner electrodes. In a mounting process, the laminated ceramic capacitors are mounted on a mounting surface such that the inner electrodes are perpendicular or substantially perpendicular to the mounting surface.

Abstract: A bit allocation method is used in an optical transmission system that transmits multicarrier signals of different wavelengths in wavelength division multiplexing. Frequency characteristics of subcarriers included in the multicarrier signals are different between the respective multicarrier signals. The method includes: measuring transmission characteristics of the subcarriers included in corresponding multicarrier signals at different subcarrier frequencies; and determining a number of bits to be allocated to each of the subcarriers included in each of the multicarrier signals based on the transmission characteristics measured at the different subcarrier frequencies.

Abstract: A transmission device is implemented in a first node in an optical transmission system in which a frame is transmitted from the first node to a second node via an optical interface. The transmission device includes a decision unit that decides whether a type of a first error correction code used in the first node is the same as a type of a second error correction code used in the second node. When a type of the first error correction code is the same as a type of the second error correction code, the transmission device transmits the frame to which an error correction code used in the first node is added to the second node without terminating the error correction code.

Abstract: An apparatus includes a receiver configured to receive a signal that has traveled an optical transmission line without returning output from an optical transmitting device and synchronize with the optical transmitting device in order to demodulate the signal; a dispersion compensator configured to compensate for wavelength dispersion caused by transmission of the signal; an acquisition circuit configured to acquire a transmitting timing at which the signal has been transmitted from the optical transmitting device; a calculation circuit configured to calculate a transmission time period from the optical transmitting device to the receiver from the transmitting timing and a receiving timing at which the signal has been received with the receiver; and an amount setting circuit configured to adjust a dispersion compensation amount of the dispersion compensator in accordance with the transmission time period.

Abstract: A transmission device includes: a plurality of modulators that respectively generate multicarrier signals from given data; a distributor that distributes input data to the modulators; an optical circuit that multiplexes the multicarrier signals to generate a WDM optical signal; and a controller that obtains allocation information from a receiver of the WDM optical signal and generates a distribution instruction to control the distributor and a bit allocation instruction to control the modulators according to the allocation information. The allocation information is calculated based on transmission characteristics of each subcarrier of the respective multicarrier signals and the allocation information indicates a number of bits of data allocated to each of the subcarriers. The distributor distributes the input data to the modulators according to the distribution instruction.

Abstract: An optical transmitter converts a plurality of transmission signals transmitted via a plurality of lanes into a multi-carrier signal and transmits the multi-carrier signal. The optical transmitter includes: a controller configured to generate allocation information that indicates an allocation of sub-carriers to the plurality of lanes according to a bit rate of the transmission signal of each of the lanes and a possible transmission capacity of each of the sub-carriers; and a signal processor configured to convert the plurality of transmission signals into the multi-carrier signal in accordance with the allocation information generated by the controller.

Abstract: An optical transmitter includes a DMT modulating unit that allocates information signals to SCs and that generates a DMT signal by performing multi-level modulation on each of the information signals allocated to each of the SCs. The optical transmitter includes a mixer that shifts, on the basis of the probe result of the DMT signal and frequency information on a wireless signal that is input, the carrier frequency of the wireless signal so as not to overlap the SC to which the information signal in the DMT signal is allocated. Furthermore, the optical transmitter includes a multiplexing unit that multiplexes the DMT signal received from the DMT modulating unit and the wireless signal in which the carrier frequency has been shifted and outputs the multiplexed signal.

Abstract: A method for estimating characteristics of an optical receiver includes: a generating process, a monitoring process, a suppressing process, a guiding process and an estimating process. The generating process generates a modulated optical signal based on an oscillation signal. The monitoring process monitors an optical spectrum of the modulated optical signal or a spectrum of an electric signal obtained by performing optical-to-electrical conversion on the modulated optical signal. The suppressing process suppresses a modulation component of an upper sideband or a lower sideband of the modulated optical signal based on the optical spectrum of the modulated optical signal or the spectrum of the electric signal. The guiding process guides the modulated optical signal in which the modulation component is suppressed to the optical receiver. The estimating process estimates the characteristics of the optical receiver based on an output signal of the optical receiver.

Abstract: There is provided a transmission apparatus includes: a first modulator configured to modulate a first electrical signal to a second electrical signal that is a multicarrier signal including a plurality of subcarriers to which transmission capacities are allocated, respectively; a light source configured to generate light having a predetermined wavelength; a second modulator configured to modulate the light generated by the light source to an optical signal, based on the second electrical signal modulated by the first modulator; and a processor configured to: measure a first frequency distribution of intensity of the second electrical signal modulated by the first modulator, measure a second frequency distribution of intensity of the optical signal modulated by the second modulator, compare the first frequency distribution and the second frequency distribution, and control modulation characteristics of the second modulator according to a result of comparing the first frequency distribution and the second frequ

Abstract: A drive circuit for a power semiconductor element includes: a voltage-command generation unit that generates a voltage command VGEref, which is a charge command between the gate and emitter terminals of a power semiconductor element; and a subtracter that calculates a deviation voltage Verr between the voltage command VGEref and the voltage between the gate and emitter terminals. The drive circuit also includes: a gate current controller that is input with the deviation voltage Verr and calculates a gate-current command voltage VIGref for determining the gate current that is caused to flow to the gate terminal of the power semiconductor element; a gate-current command limiter that limits the gate-current command voltage VIGref; and a gate-current supply device that is input with an actual gate-current command voltage VIGout and that supplies a gate current to the gate terminal of the power semiconductor element.

Abstract: An optical transmission device includes an error correction scheme determining unit, an error correction encoder, a modulation format determining unit and an optical transmitter. The error correction scheme determining unit determines an error correction scheme based on a latency between the optical transmission device and a correspondent device. The error correction encoder generates encoded data by performing an error correction encoding on transmission data using the error correction scheme determined by the error correction scheme determining unit. The modulation format determining unit determines a modulation format based on the error correction scheme determined by the error correction scheme determining unit and transmission characteristics between the optical transmission device and the correspondent device. The optical transmitter generates a modulated optical signal from the encoded data with the modulation format determined by the modulation format determining unit.