Oki Electric Industry Co., Ltd.

Nec Corporation

Hitoshi Murai

Kengo Koizumi

Shin Arahira

Masatoshi Kagawa

Hideyuki Iwamura

Tadashi Kishimoto

Tokuo Yamaguchi

Kenji Suehiro

Kouji Inafune

A self-delayed homodyne interferometer includes light source unit, a splitting unit, an interference signal acquisition unit, a scattered light intensity acquisition unit, and a signal processing unit. The light source unit generates probe light. The splitting unit splits into two branches, Brillouin backscattered light occurring in an optical fiber to be measured with the probe light. The acquisition unit receives scattered light of one branch, and uses a self-delayed homodyne interferometer to generate an interference signal. The acquisition unit receives scattered light of the other branch, and acquires intensity of the scattered light. The signal processing unit separates and acquires a frequency shift amount from the intensity of the interference signal, and strain and temperature change from the intensity of the scattered light. The acquisition unit can change a phase of the scattered light of the one of the two branches.

Optical fiber strain and temperature measurement apparatus and optical fiber strain and temperature measurement method

By removing remaining components of Rayleigh scattered light, control is sufficiently performed of polarization states even when the wavelength of scattered light has changed. A light source unit configured to generate probe light, a wavelength control unit configured to receive backscattered light emitted from an optical fiber to be tested by the probe light and to output Brillouin backscattered light included in the backscattered light, and a self-delayed heterodyne interferometer to which the Brillouin backscattered light is input are included. The wavelength control unit includes a wavelength separation filter, a variable wavelength filter, an optical intensity measurement unit, and a control unit. The wavelength separation filter has two output ports, outputs and transmits, from one of the two output ports, the Brillouin backscattered light to the variable wavelength filter, and outputs and transmits, from the other output port, Rayleigh scattered light to the optical intensity measurement unit. The optical intensity measurement unit measures a center wavelength and a peak intensity of the Rayleigh scattered light. The control unit controls a cutoff wavelength of the variable wavelength filter in accordance with a direction and amount of change of the center wavelength.

Optical fiber strain and temperature measurement apparatus

An optical amplification device includes a first optical amplification portion, an intermediate portion and a second optical amplification portion. The first optical amplification portion receives input light including signal light and pump light, generates idler light as wavelength converted light based on wavelengths of the signal light and the pump light, and outputs first output light including signal light, pump light and idler light. The intermediate portion outputs second output light, and includes a demultiplexing portion that demultiplexes the first output light into signal light, pump light and idler light, a multiplexing portion that generates the second output light by multiplexing signal light, pump light and idler light, and a polarization plane adjustment portion that exchanges mutually orthogonal polarization components of idler light. The second optical amplification portion amplifies an intensity of signal light included in the second output light.

Cascaded optical parametric amplifier with polarization exchange for noise reduction

A first wavelength converter of a wavelength-conversion device includes: an optical amplifier amplifying an incident light beam; a first dispersion flat fiber spreading the wavelength spectrum width of the amplified beam; and a first wavelength filter transmitting a predetermined wavelength bandwidth of the first fiber output beam. A center wavelength of the first wavelength converted beam is shifted by &#x394;&#x3bb;from that of the incident light beam. A second wavelength converter of the device does not include an optical amplifier and includes: a second dispersion flat fiber spreading the wavelength spectrum width of the first wavelength converted beam; and a second wavelength filter transmitting a predetermined wavelength bandwidth of the second fiber output beam. A center wavelength of the second wavelength converted beam is shifted by &#x394;&#x3bb;from that of the first wavelength converted beam. The &#x394;&#x3bb;and &#x394;&#x3bb;satisfy &#x394;&#x3bb;, and |&#x394;

Wavelength conversion device and wavelength conversion method

An optical signal generator includes a splitter, a first modulator, a second modulator, a signal-switching unit and a multiplexer. The splitter splits an optical pulse train into a first pulse train and a second pulse train. The first modulator receives the first pulse train and first data signal, and generates a first modulation signal by performing on-off-keying or phase modulation on the first pulse train based on the strength of the first data signal. The second modulator receives the second pulse train and second data signal, and generates a second modulation signal by performing the on-off-keying or phase modulation on the second pulse train based on the strength of the second data signal. The signal-switching unit delays pulses of the second modulation signal or adjusts a phase of a carrier included in the second modulation signal according to a switching signal. The multiplexer generates an optical modulation signal by multiplexing the first modulation signal and the second modulation signal.

Optical signal generator

An optical modulator includes, a first polarization separation and combination portion, a second polarization separation and combination portion, a first polarization plane-maintaining optical fiber, a second polarization plane-maintaining optical fiber, a third polarization plane-maintaining optical fiber of which a first end is coupled with the second input and output terminal of the second polarization separation and combination portion, the third polarization plane-maintaining optical fiber including a first optical coupler, to which control light that is linearly polarized light is input, a fourth polarization plane-maintaining optical fiber of which a first end is coupled with the third input and output terminal of the second polarization separation and combination portion; and a first polarization plane conversion portion that optically communicates with a second end of the third polarization plane-maintaining optical fiber and a second end of the fourth polarization plane-maintaining optical fiber.

Optical modulator and optical signal generation apparatus

A wavelength conversion device that obtains, from an input light, a wavelength-converted light with a wavelength shift by a wavelength shift amount of &#x394;&#x3bb; is disclosed. The device comprises first and second wavelength converters. The first wavelength convertor shifts a central wavelength of a first wavelength-converted light by a first wavelength shift amount of &#x394;&#x3bb;relative to a central wavelength of an input light. The second wavelength convertor shifts a central wavelength of a second wavelength-converted light by a second wavelength shift amount of &#x394;&#x3bb;relative to a central wavelength of the first wavelength-converted light. The first wavelength shift amount of &#x394;&#x3bb;and the second wavelength shift amount of &#x394;&#x3bb;satisfy &#x394;&#x3bb;

An optical transmission line allows optical signals to be transmitted with higher stability over longer distances. According to a first aspect, an optical NRZ signal is split in two, one half is presented to a clock extraction circuit, and the other half is presented to an EA modulator. An optical RZ signal is obtained as an output because the EA modulator is energized by the provided clock component. According to a second aspect, a nonlinear phase shift based on cross-phase modulation is induced in an RZ pulse train by an optical NRZ signal, and only the RZ pulses corresponding to the optical NRZ signal are extracted. According to a third aspect, first dispersion compensator is provided to a preceding stage of an optical fiber transmission line for transmitting optical pulses, and second dispersion compensation compensator is provided to a subsequent stage. Pulse widening in the optical fiber transmission line is controlled by a nonlinear chirp induced in the first dispersion compensator.

Optical signal generating circuit and optical transmission line

An optical communications apparatus that is superior in terms of the quality of long-distance transmission. The optical communications apparatus has a plurality of time-division multiplexing devices and an optical multiplexer. Each of time-division multiplexing devices generates optical data sequences by subjecting two systems of optical signal sequences to time-division multiplexing. In each optical data sequence, the duty ratio of the optical pulses is 0.5 or greater, and the phase difference between adjacent optical pulses is &#x3c0; phase. Moreover, the optical multiplexer subjects the optical data sequences input from the plurality of transmitters to wavelength-division multiplexing. Since the duty ratio is set at 0.5 or greater and the phase difference is set at &#x3c0; phase, the soliton interaction of the optical signal sequences and the interaction between channels can be reduced, so that the reliability of the transmitted data is improved.

Optical communications apparatus and optical communications system

A method of, apparatus for and computer-readable medium for obtaining a program for a distributed memory-type parallel computer by dividing data for a program written for a serial processing computer. The method comprises changing a declaration of an array to be subjected to indirect or irregular division which is designated by the mapping array in the program into a declaration of an allocation array; inserting statements to declare the allocation array for converting subscripts and to calculate the size of the divided array during processing, and inserting a statement to preserve or to release an area for divided arrays corresponding to the calculated length of arrays to be divided and subscript conversion arrays during processing.

Method of, apparatus for, and recording medium storing a program for, parallelizing a program containing an array designated to undergo indirect and irregular division

The present invention relates to an optical short pulse generator using an EA modulator. In addition to continuous wave light for generating an optical short pulse train, pump light for generating a pile up is injected into this EA modulator. Generating a pile up increases the number of photo-carriers which accumulate in the light absorption layer without being swept out to the clad layer, and this increases the change in the light absorption quantity when a sinusoidal electric field is applied to the EA modulator. The EA modulator in accordance with the present invention has excellent extinction characteristics so that it can generate an optical short pulse train whose loss is small and pulse width is very small. According to one preferred embodiment of the present invention, the pump light is injected into the light absorption layer of the EA modulator, not from the end face where continuous wave light is injected, but from the end face where the optical short pulse train is emitted.

Growing community of inventors

Tokyo, Japan

Hitoshi Murai