Fujitsu Corporation

Fujitsu Optical Components Limited

Yuji Ishii

Kazuyuki Mori

Kenji Rikimaru

Yuji Tochio

Tamotsu Akashi

Shinji Yamashita

Naoyuki Takeshita

Shinichirou Miyajima

Kenichi Kawazoe

Katsuhiro Eguchi

Takashi Shimizu

Hisao Nakashima

Koji Terada

Ichiro Watanabe

Yoshio Sakai

Tetsuji Yamabana

Kiichi Sugitani

Kazuyuki Inomoto

Tetsuya Yasui

Kazunari Shiota

Yuji Nagano

Kazuhiro Ichiyanagi

Hiroshi Adachi

Toshikazu Senuki

Jun Endoh

Akiko Kusumoto

Masahiro Abe

Hiroshi Onimaru

An optical receiver receives coherent light. The optical receiver includes an amplitude adjuster, a signal processor, and a controller. The amplitude adjuster adjusts amplitude of an input signal to output an analog signal. The signal processor receives a digital signal generated from the analog signal output from the amplitude adjuster, extracts clock components from the digital signal, and after establishing synchronization between the clock components and data components, extracts the data components from the digital signal to process the data components. The controller sets amplitude of the analog signal to first amplitude before establishment of synchronization by the digital signal, and changes the set amplitude to second amplitude that is smaller than the first amplitude after the establishment of synchronization.

Optical receiver and light receiving method

An electronic device includes: a detection circuit to detect a voltage difference between both ends of a wiring portion which is at least a portion of a power supply wiring that connects a power supply circuit and a receiver circuit; a current supply circuit to supply a pilot current having a first current value which is smaller than a second current value of a main current to the power supply wiring; and a control circuit to control supply of the pilot current and stop of the supply of the pilot current, to calculate a wiring resistance value of the wiring portion based on a first value of the voltage difference when the supply is stopped, a second value of the voltage difference when the pilot current is supplied, and the first current value and to calculate the second current value based on the first value and the wiring resistance value.

Electronic device and current monitoring method

An optical modulation device includes a generating circuit that generates a low-frequency signal, an average value of amplitude as an alternating-current component of the low-frequency signal being different from a center value of the amplitude of the low-frequency signal, a superimposing unit that superimposes the low-frequency signal on a data signal, an optical modulator that modulates, using the superimposition of the low-frequency signal by the superimposing unit, light from a light source and outputs a light signal, a calculating circuit that calculates an amplitude average value and an amplitude center value of a low-frequency component obtained from the light signal output by the optical modulator, and a controller that controls a bias voltage of the optical modulator such that the amplitude average value is brought closer to the amplitude center value of the frequency component calculated by the calculating circuit.

Optical modulation device and bias voltage control method

A phase synchronization method uses a removal path for removing an error component contained in an input signal and a delay addition path for adding a delay corresponding to a processing time period taken to remove the error component in the removal path. The removal path includes an averaging section. The averaging section includes a shift register and an obtaining unit. The shift register stores as many data as the maximum number of data to be averaged and successively receives processing data from which the error component has been extracted in the removal path. The obtaining unit obtains, among the successive processing data input to the shift register, as many processing data as the number of data to be averaged from a position near the center toward both ends in the shift register.

Phase synchronization apparatus and digital coherent light receiver

A mirror driving circuit applies a voltage to drive a mirror and switches an optical path of light output from a channel of an input port to a channel of an output port. The mirror driving circuit includes an offset-voltage applying unit that applies an offset voltage to the mirror, an applied-voltage determining unit that determines an applied voltage to be applied to the mirror based on a relation between the channel of the input port and the channel of the output port forming a path of the light, and a voltage applying unit that applies to the mirror a remaining voltage obtained by subtracting the offset voltage from the applied voltage.

Mirror driving circuit and optical switch

An optical transmission system () alters quantity of incident light by reflecting an optical signal by a micro mirror () to enter an optical fiber () and by controlling an angle of the micro mirror (), so that attenuation of the optical signal is controlled. An optical filter () is disposed between the micro mirror () and the optical fiber (), for correcting a relationship between a control angle or control voltage of the micro mirror () and attenuation of the optical signal to be close to a linear relationship.

Optical transmission system

An optical switching system includes a connection information memory portion () that stores connection information between input ports and output ports, a control characteristic memory portion () that stores control characteristic data of micro mirrors with respect to each of a plurality of temperatures, a temperature sensor () that senses a temperature in the optical switching system, and a computing portion () that refers to the control characteristic data stored in the control characteristic memory portion so as to calculate a controlled variable for the angle control of the micro mirrors based on the connection information stored in the connection information memory portion and the temperature sensed by the temperature sensor.

Optical switching system and control method for micro mirror

An optical switch system has a plurality of micro mirrors arranged in a plane, and an angle of each of the micro mirrors can be controlled for reflecting an optical signal entered from one or more input ports so that the reflected optical signal enters a selected output port of one or more output ports. The optical switch system includes a storage portion for storing connection information between the input port and the output port, a correction quantity obtaining portion for obtaining a correction quantity for a cross talk generated between neighboring micro mirrors among the plurality of micro mirrors, a computing portion for determining a controlling quantity of the micro mirror in accordance with the connection information and the correction quantity, and a drive output portion for driving the micro mirror in accordance with the controlling quantity.

Optical switch system

A communication system that can improve communication quality by accurately re-creating reproduction timing at the receiving end even at the time of receiving VBR data or in the case of the occurrence of a packet loss. A send rate recognition section recognizes a send rate from a time stamp. A memory stores data. A dummy data addition section adds dummy data for correcting the difference between a read rate set for reading out data from the memory and the send rate to the data written to the memory. A read clock generation section generates a read clock which is equal to the read rate. A dummy data removal section removes the dummy data from the data read out from the memory on the basis of the read clock.

Communication system

In a digital filter device which filters a plurality of signals by a single digital filter, an input data memory stores the input data strings generated by computing processors, and a digital filter reads the input data strings in a predetermined sequence to be filtered and generates output data strings. An output data memory stores the output data strings, and a data processor reads the output data strings in a predetermined sequence to be processed. Furthermore, a filter memory and coefficient memories respectively store data-under-calculation and a filter coefficient in a delay circuit included in the digital filter.

Digital filter device

A mirror controller of an optical switch comprises a signal generator () for passing the optical signal on the same light path as the one for optical communication using the optical switch, and an image analyzer () detecting the optical signal as the light scattered by at least one of tilt mirrors () and an output collimator array (). The image analyzer detects the position of the light beam image as a control position () based on the scattered light, and controls the tilt mirrors in such a manner that the detected control position coincides with the predetermined desired target position () on at least one of the tilt mirrors and the output collimator array. The mirror controller can realize the connection test of the optical signal between input and output with high accuracy and reliability.

Mirror controller for optical switch

An object of the invention is to provide a control apparatus and a control method having a simple constitution, which can stably perform switching of optical path in an optical signal exchanger, while suppressing an influence on a control due to the mechanical resonance of tilt mirrors. To this end, the control apparatus of the optical signal exchanger is constituted such that in an optical signal exchanger of three-dimensional type using one set of MEMS mirror arrays, each having a plurality of tilt mirrors arranged on a plane, each tilt mirror having a reflecting surface an angle of which is controllable, when the angle of the MEMS mirror on the optical path is feedback controlled by detecting power of an optical signal output from a specific position, a resonance component removing section that removes a resonance frequency component included in a control signal is shared corresponding to a pair of driving electrodes arranged in a coaxial direction of the MEMS mirror. As a result, the influence on the feedback control by a resonance action of the MEMS mirror can be reduced, while suppressing an increase in circuit size.

Control apparatus and control method of optical signal exchanger

If a radio LAN apparatus moves from a communication range of a first access point to a communication range of a second access point, and if communication link between the radio LAN apparatus and the first access point is broken, a memory control section stops transmitting data to the first access point. At this time, data to be transmitted to the first access point are not deleted from memory. After the radio LAN apparatus enters the communication range of the second access point, the memory control section resumes transmission of the data stored in the memory. Thereafter, the next data are transmitted. Thus, the data is transmitted in proper sequence.

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Fukuoka, Japan

Yuji Ishii