Fujitsu Corporation

Mitsubishi Denki Kabushiki Kaisha

Taku Saito

Kosuke Komaki

Hirofumi Araki

Taketo Endo

Osamu Takeuchi

Katsumi Fukumitsu

Hiroshi Nishida

Makoto Shimizu

Shoichi Murakami

Shuzo Matsushita

Takeshi Hoshida

Zhenning Tao

Hisao Nakashima

Nobukazu Koizumi

Ying Zhao

Liang Dou

Kozo Baba

Yoshitaka Taki

Akiyoshi Tafuku

Hisao Ito

Kanji Naito

Hisayuki Ojima

Taku Katagiri

Masatoshi Tohno

Yoshinori Tochiki

Yuji Kamura

Hironobu Hongou

Daijiro Tanaka

Satoru Miyazaki

Masamichi Sugamoto

An optical apparatus includes an attenuator, a photoelectric convertor, an amplifier, and a processor. the attenuator attenuates signal light. The photoelectric convertor converts the signal light attenuated by the attenuator into an electric signal. The amplifier adjusts a gain of the electric signal. The processor detects a monitor value of a target channel from an output signal of the amplifier, calculates a power value of the target channel from the detected monitor value, calculates a difference value between the power value and a target power value, calculates a attenuation amount by adding a current attenuation amount, which is currently set to the attenuator, to the difference value, controls the gain of the amplifier so that the difference value of the target channel is minimized when the set attenuation amount is less than zero, and sets the attenuation amount to the attenuator when the attenuation amount is zero or more.

Optical apparatus and optical receiving method

There is provided an optical transmitter including a memory, a processor coupled to the memory and the processor to generate an electric signal, an optical generator to generate light, an optical modulator to modulate the light with the electric signal to create an optical signal, a first voltage electrode to apply a first voltage to the optical signal, a second voltage electrode to apply a second voltage to the optical signal to which the first voltage is applied, and a detector to detect an optical power of the optical signal to which the second voltage is applied, wherein the processor stops generating the electric signal, controls the first voltage electrode to change the first voltage after the stop of generating the electric signal, and controls the second voltage electrode to change the second voltage according to the detected optical power after the change of the first voltage.

Optical transmitter

An optical transmission apparatus may include a coherent detector, a photoelectric converter, an amplifier, a gain controller, and an optical power monitor. The coherent detector may perform a coherent detection on received light including a plurality of wavelengths to select light having any one of the wavelengths. The photoelectric converter may convert the light having the selected wavelength to an electrical signal. The amplifier may amplify the electrical signal. The gain controller may control a gain of the amplifier depending on an output amplitude of the amplifier. The optical power monitor may calculate an optical power level of the selected wavelength based on the gain and the output amplitude.

Optical transmission apparatus, optical power monitor, and method of monitoring optical power

An optical transmission apparatus includes: a coherent detector configured to receive light including different polarization components from an optical transmission path, and perform coherent detection of received light including the different polarization components; an adaptive equalizer configured to adaptively equalize, by a digital filter, a complex electric signal for each of the polarization components obtained by the coherent detection, a gain value for controlling an amplitude of the complex electric signal being applied to the complex electric signal; and a polarization dependent loss monitor configured to determine a polarization dependent loss of the optical transmission path, based on a correction filter parameter obtained by correcting a filter parameter of the digital filter according to the gain value, the filter parameter being adaptively updated by an adaptive equalization of the adaptive equalizer.

Optical transmission apparatus, optical transmission system, and polarization dependent loss monitor

An optical transmission apparatus for transmitting wavelength-multiplexed light, the optical transmission apparatus includes: an optical transmitter configured to transmit light of a third wavelength to be arranged between a first wavelength and a second wavelength adjacent to the third wavelength in the wavelength-multiplexed light, and a controller configured to control a bandwidth of the light of the third wavelength to be arranged in a first bandwidth narrower than a spacing between the first wavelength and the second wavelength.

Optical transmission apparatus, optical transmission system, and transmission wavelength control method

A method and apparatus for correcting inter-channel power imbalance and a receiver, applicable to a receiver in a multicarrier optical communication system, where the method includes: receiving by the receiver reference information transmitted by a neighboring receiver; and performing power imbalance error correction by the receiver according to the reference information. With this application, based on performing signal processing in the receiver, estimation errors produced due to power imbalance in the central channel and the neighboring channel may be reduced.

Method and apparatus for correcting inter-channel power imbalance and receiver

An optical transmission apparatus includes: a plurality of optical transmitters configured to transmit optical signals having variable wavelengths, respectively; a multiplexer configured to wavelength-multiplex the optical signals transmitted from the plurality of optical transmitters in a transmission band of an optical device through which the optical signals is transmitted; and a controller configured to control, in response to nonexistence of an optical signal having a second wavelength adjacent to a first wavelength closest to an outer edge of the transmission band in the optical signals, an optical transmitter corresponding to the first wavelength so as to shift the first wavelength in a direction toward the second wavelength.

Optical transmission apparatus and wavelength control method

An optical transmission apparatus includes: an optical receiver configured to receive an optical signal; a variable optical attenuator configured to adjust a power of the optical signal to be input to the optical receiver according to a variable attenuation amount; and a controller configured to control the attenuation amount of the variable optical attenuator based on an electrical signal obtained by performing a coherent detection and a photoelectric conversion on the optical signal received by the optical receiver.

Optical transmission apparatus and method for controlling optical power

An optical transmission system includes comprising: a first optical transmission apparatus to transmit wavelength-multiplexed optical signals; and a second optical transmission apparatus to receive the wavelength-multiplexed optical signals, the second optical transmission apparatus including: a receiver to perform digital coherent reception; a wavelength spacing monitor to transform a reception signal obtained by the digital coherent reception from a time domain signal to a frequency domain spectrum signal, and to monitor wavelength spacing of the spectrum signal; and a transmitter to transmit, to the first optical transmission apparatus, wavelength control information according to a monitor result obtained by the wavelength spacing monitor or the monitor result, wherein the first optical transmission apparatus includes: a receiver to receive the wavelength control information or the monitor result; and a control unit to control the wavelength spacing based on the wavelength control information or the monitor result received by the receiver.

Optical transmission system, optical transmission apparatus and wavelength spacing measurement apparatus

An optical transmission system includes: a transmission node to transmit wavelength-multiplexed light of a plural wavelengths arranged in a predetermined transmission band; and a reception node to receive the wavelength-multiplexed light, and to include a monitor to monitor a detection sensitivity indicating a sampling phase shift with respect to a phase of light corresponding to one among the received plural wavelengths, and a transmitter to transmit information indicating that the monitored detection sensitivity for light corresponding to a wavelength adjacent to an outer edge of the transmission band, among the plural wavelengths, has been reduced below a threshold value, to the transmission node, wherein the transmission node includes a receiver to receive information indicating a reduction in the detection sensitivity, and a controller to stop wavelength control of shifting the wavelength adjacent to the outer edge in a direction approaching the outer edge in response to reception of the information.

Optical transmission system, wavelength control method and node

An optimization unit in an optical receiver divides a symbol region out of a plurality of symbol regions into which signal points that specifies symbol information included in an optical signal are classified, into a plurality of division regions from the symbol center coordinate of the symbol region. Moreover, the optimization unit accumulates the signal points of the symbol information for every division region in the symbol region. Furthermore, based on the accumulated number of signal points for every division region, the optimization unit controls the average length of a phase estimation unit when the phase noise of the optical signal is calculated.

Optical signal processing device, optical signal processing method and recording medium

An optical transceiver converts a received optical signal to an electric signal and converts the electric signal to a digital signal, and has an adaptive equalizer to adaptively equalize the digital signal, a synchronization part to synchronize a first polarized wave and a second polarized wave contained in the adaptively equalized digital signal and having polarization axes perpendicular to each other, and a symbol offset determination part to determine an amount of symbol offset between the first polarized wave and the second polarized wave based upon symbol synchronization information of the first polarized wave and the second polarized wave supplied from the synchronization part, the symbol offset determination part being configured to repeat determination of the amount of symbol offset and restart the adaptive equalizer until the symbol offset is minimized.

Optical receiver and signal processing method for optical receiver

A method of tap coefficient correction includes: obtaining a synchronization symbol difference between a first polarization and a second polarization orthogonal to the first polarization; obtaining a delay amount of each of the first polarization and the second polarization in an adaptive equalizer; calculating, in a case where a horizontal axis represents a tap number and a vertical axis represents a tap coefficient and a tap number or a nearest tap number with which an area of a drawn figure is halved is set as a gravity center of tap coefficients, a correction reference gravity center of the tap coefficients set in the adaptive equalizer, based on the synchronization symbol difference and the delay amount; and performing a correction of shifting an entire tap coefficients in units of symbol to cause the correction reference gravity center to be closest to a tap center.

Adaptive equalizer tap coefficient correction method and optical receiver

Provided are an image processing method, an image processing system, an image processing device and a computer program for detecting a detection object such as nares of the driver with a high degree of accuracy in, for example, a system using an in-vehicle camera which is mounted on a vehicle and takes an image of the face of the driver. A detection object is diversified by a variety of detection methods such as a method for detecting a plurality of locations in the vertical direction as candidates during image pickup of an image, detecting a range to be a candidate of a detection object on the basis of the brightness of a pixel for each of rows of pixels lined up in the horizontal direction corresponding to each detected location and specifying a detection object from candidates of a detection object on the basis of the length of the detected range.

Image object detection using separate ranges from both image detections

A moving picture receiving method for receiving a moving picture by block unit includes steps of detecting a lost block which can not be reproduced in the receiving image signal, calculating an average value of blocks adjacent to the lost block which can not be reproduced, adaptively substituting the lost block by an average value of the block adjacent to the lost block or a block at the same location corresponding to the preceding frame in case that the block is lost in the receiving signal.

Growing community of inventors

Kawasaki, Japan

Taku Saito