Fujitsu Corporation

Matsushita Electric Industrial Co., Ltd.

Fujitsu Telecom Networks Limited

Tsukasa Takahashi

Koichi Ogawa

Toshihiro Ohtani

Hiroyuki Itou

Hiroshi Iwai

Kazuo Yamane

Kenichi Yamada

Yumiko Kawasaki

Yuji Tamura

Michikazu Shima

Atsushi Yamamoto

Shinji Kamaeguchi

Yoshio Koyanagi

Futoshi Izumi

Shota Mori

Hideki Kobayashi

Hiroto Ikeda

Kazuhiro Suzuki

Miki Onaka

Norifumi Shukunami

Yoichi Oikawa

Masahiro Yuki

Takashi Tsuda

Ryosuke Goto

Tatsuya Tsuzuki

Yasunori Nagakubo

Hiroshi Iizuka

Hiroyuki Deguchi

Shinji Komiya

Kazuhiro Kunimatsu

Yuji Miyaki

Yoshinori Ohkuma

Togo Fukushi

Eiji Ishikawa

Masayoshi Hirai

Keisuke Imai

Kazuto Imai

Kazuhiko Ohta

An optical switch include a switch unit including a light reflection unit of which the reflection direction is changeable, the switch unit configured to optically connect an input port to an output port via the light reflection unit by changing the reflection direction of the light reflection unit; a determining light input unit configured to input into a first predetermined port a determining light for determining malfunctions in the light reflection unit; a light detection unit configured to detect the determining light from the output from a second predetermined port; and a malfunction determining unit configured to determine that abnormalities have occurred when the determining light is detected by the light detection unit.

Optical switch

An optical transmission apparatus includes a non-reciprocal device including first to second ports, an optical signal input from the first port being provided to the second port, an optical signal input from the second port being provided to the first port, a dispersion compensator that is coupled to the first port of the non-reciprocal device and that conducts given processing to an optical signal input from the first port of the non-reciprocal device to provide the optical signal subjected to the given processing to the second port of the non-reciprocal device, a first monitor, a second monitor, and a fault determination device that compares a value monitored by the first monitor with a value monitored by the second monitor to determine one of a connection failure, at least at one of the first port, the second port, of the non-reciprocal device and a connection state of the dispersion compensator.

Optical transmission apparatus and fault detection method

A dispersion compensating apparatus includes a tunable dispersion compensator that dispersion-compensates an optical signal using a group delay property that is asymmetrical in bands outside an effective band; a set device that sets a dispersion compensation amount in the tunable dispersion compensator; and a shifter that shifts a central frequency of the effective band of the tunable dispersion compensator, based on the dispersion compensation amount set by the set device.

Dispersion compensating apparatus, dispersion compensating method, optical receiving apparatus, and optical receiving method

An optical reception device is provided. The optical reception device includes a filtering unit that receives input light of predetermined power, filters the input light by use of filter characteristics where the degree of attenuation of the power of an optical signal of predetermined frequency is lower than the degree of attenuation of the power of an optical signal of another frequency, and supplies an output light; and a determining unit that compares a value relevant to the power of the output light supplied by the filtering unit, with a threshold, and determines whether the input light contains signal light.

Optical reception device, optical receiving method, and optical transmission apparatus

A dispersion compensation device includes a variable dispersion compensator configured to subject an input optical signal to dispersion compensation, an optical receiver configured to convert an optical signal subjected to dispersion compensation into an electrical signal, recover a clock signal and a received data signal from the electrical signal, and output clock lock information indicating whether the clock signal is locked to the electrical signal, a signal processor configured to output bit error rate information on the received data signal, and a controller configured to variably control a dispersion compensation value of the variable dispersion compensator based on the bit error rate information and the clock lock information.

Variable dispersion compensation device

A signal detection method used in an optical receiver apparatus detects the variation of an optical input level from the presence or absence of a clock signal and appropriately controls a dispersion compensator, thereby enabling the presence or absence of an input signal to be correctly determined. The signal detection method includes: detecting the level of input light of an optical amplifier, storing the level of the detected input light, comparing the level of the stored previous input light with the level of current input light, detecting the level variation of the input light by the comparison to detect the state change of the presence or absence of an optical signal, performing a dispersion compensation on the input light, and extracting a clock from an optical input. When the level variation of the input light is detected, the presence or absence of the optical signal of the input light is determined from the presence or absence of the clock signal. When the clock signal is not extracted, the dispersion amount is swept.

Optical signal detection method, and light receiving apparatus using the same

In an optical transmission network of the present invention, an optical signal output from a CWDM unit is combined on an optical transmission path of a DWDM network via a multiplexing filter arranged on a light output terminal of a DWDM unit adjacent to the CWDM unit. Furthermore, an optical signal propagated on an optical transmission path is branched from the DWDM light by a de-multiplexing filter provided on a light input terminal of an adjacent DWDM unit, and applied to a CWDM unit adjacent to the DWDM unit. As a result, it is possible to mutually connect a plurality of CWDM networks, using an optical transmission path of a DWDM network, and it is possible to realize a longer distance for CWDM networks.

Optical transmission network

In an optical transmission system: a first unit generates a first optical supervisory signal being arranged on the shorter-wavelength side of main signals and containing information for determining continuity of an optical transmission line and a second optical supervisory signal arranged on the longer-wavelength side of the main signals and used for supervisory control of optical communication; a second unit generates a wavelength-multiplexed signal by optically multiplexing the main signals and the first and second optical supervisory signals, and transmits the wavelength-multiplexed signal onto the optical transmission line; a third unit receives the wavelength-multiplexed signal, and optically demultiplexes the wavelength-multiplexed signal into the main signals and the first and second optical supervisory signals; and a fourth unit determines whether or not the optical transmission line is optically continuous, based on the first optical supervisory signal, and performs supervisory control of optical communication based on the second optical supervisory signal.

Optical transmission system

An optical terminal apparatus includes a plurality of signal light units that transmits and receives a signal light having a predetermined wavelength; at least one pumping light unit that emits a pumping light having a predetermined wavelength to perform Raman amplification for the signal light transmitted; and an optical multiplexer/demultiplexer that multiplexes/demultiplexes the signal light and the pumping light, the optical multiplexer/demultiplexer having one end connected to an optical transmission path and other end connected to the signal light units and the pumping light unit.

Optical terminal apparatus

A reliable optical transmission system with an improved signal control mechanism that avoids abrupt power variations of light beams, thereby preventing optical supervisory channel (OSC) signals from experiencing errors. An optical amplifier amplifies main signals under the control of an optical amplifier controller, which spends a first predetermined time to raise the output power of the optical amplifier up to a desired level. A pump light source produces a pump beam for injection to a fiber-optic transmission line so as to make it serve as an amplifying medium. The pump light source is controlled by a pump light source controller that spends a second predetermined time to raise the pump beam to a desired power level. This stepwise start-up process of the amplifier power and pump beam power prevents OSC signals from experiencing abrupt power variations.

In a cellular phone terminal foldable by a hinge and including upper and lower split pieces, monopole antennas are formed on a flexible printed wiring board and a printed wiring board and a lower housing is formed with a finger grip portion such that not only deterioration of characteristics is prevented but the lower housing can be held easily.

Cell phone

A small-sized mobile radio has a built-in antenna is high enough to enhance the antenna characteristics. In the mobile radio, a base plate is structured by a section (antenna-housing section) including a supply portion and a short-circuiting portion, for example, of an antenna element which affect the antenna characteristics, and a section (circuit-housing section) which is the rest of the base plate. The antenna-housing section is so positioned so as to keep the built-in antenna high enough, that is, to keep the space between the base plate and the antenna element large enough. On the other hand, the circuit-housing section is positioned toward the back of the cabinet to provide room for a display and a key section.

Mobile radio

Disclosed herein is a method including the steps of wavelength division multiplexing a plurality of optical signals having different wavelengths to obtain resultant WDM signal light; transmitting the WDM signal light by an optical fiber transmission line; supplying reference light having a predetermined wavelength to the optical fiber transmission line; generating four-wave mixing in the optical fiber transmission line by the interaction of the WDM signal light and the reference light; detecting the power of light generated as the result of the four-wave mixing; and controlling the power of the WDM signal light to be supplied to the optical fiber transmission line according to the power detected. According to this method, the effect of four-wave mixing can be suppressed.

Method and device for optical fiber transmission

A Raman excitation control method enabling to reduce the number of couplers and photodetectors (PD) for providing an optical transmission unit with reduced cost. The method is provided for use in optical amplification to amplify an optical signal using Raman excitation light fed into an optical transmission line. A backward light of a laser diode producing the Raman excitation light is monitored by an optical back power monitor. The monitored power value is compared with an initial set value stored in a memory for the laser diode. Based on this comparison result, a feedback control is performed against the light emission power of the laser diode.

Raman excitation control method and optical transmission system using the same

An inverted F-type antenna apparatus is provided with a grounding conductor and an antenna element arranged on the grounding conductor so as to face the grounding conductor. The inverted F-type antenna apparatus further includes at least one coupling element provided between the grounding conductor and the antenna element so as to face the grounding conductor and the antenna element, and a connection conductor is provided for electrically connecting the antenna element with the grounding conductor at least in one place. In the inverted F-type antenna apparatus, the grounding conductor, the antenna element and the coupling element are arranged so as to be substantially parallel to each other.

Growing community of inventors

Kawasaki, Japan

Tsukasa Takahashi