The Furukawa Electric Co., Ltd.

Japan Science and Technology Agency

Misao Sakano

Osamu Aso

Masateru Tadakuma

Takeshi Nakajima

Koji Fujimura

Katsutoshi Takahashi

Yu Mimura

Masami Ikeda

Shu Namiki

Shunichi Matsushita

Shinichi Mukoyama

Takashi Shimano

Shunichi Matushita

Shigehiro Takasaka

Yasuyuki Ozeki

A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.

Synchronous optical signal generating device and synchronous optical signal generating method

A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of the optical fiber are simultaneously specified.

System for measuring the wavelength dispersion and nonlinear coefficient of an optical fiber

A Raman amplifying device includes a plurality of Raman amplifiers having a gain wavelength characteristic with a gain peak at which an amplification gain becomes the largest, including a first Raman amplifier having a gain wavelength characteristic with a plurality of gain peaks including a first gain peak and a second gain peak adjacent to the first gain peak; a second Raman amplifier having a gain wavelength characteristic with at least one gain peak including a third gain peak between the first gain peak and the second gain peak; and a third Raman amplifier having a gain wavelength characteristic with a fourth gain peak between the first gain peak and the third gain peak, the fourth gain peak forming an arithmetic sequence between the first gain peak and the third gain peak.

Raman amplifying device and Raman amplifying system

An apparatus, method and computer program product for controlling pumping light powers for a multiple-wavelength-pumped Raman amplifier that is pumped by pumping lights from a plurality of pumping light sources, by measuring gain wavelength characteristic or signal-power wavelength characteristic of the multiple-wavelength-pumped Raman amplifier using a plurality of photodetectors having different wavelength-sensitivity characteristics. The apparatus includes a determining unit that estimates a power of each of signal channels in a wavelength band for use based on values monitored by the photodetectors, and determines the pumping light powers using the power of each of the signal channels estimated. The determining unit estimates the power of each of the signal channels by performing an interpolation of the values monitored by the photodetectors.

Method and apparatus for controlling multiple-wavelength-pumped Raman amplifier and computer product

A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as a an inexpensive light source producing a plurality of optical frequencies.

Multi-frequency light source

Raman amplifying device and raman amplifying system

A multiple-wavelength-pumped Raman amplifier includes a control unit that controls, based on a relational expression associating an amount of fluctuation in a current signal light power at a signal input end, an amount of fluctuation in a current pumping light power at a pumping light input end, an amount of fluctuation in the current signal power at a signal output end, and an amount of fluctuation in the current pumping light power at a pumping light output end, two fluctuation amounts by determining other two fluctuation amounts in advance, to determine pumping light powers satisfying the relational expression.

Method and apparatus for controlling multiple-wavelength-pumped raman amplifier and computer product

Method and system for measuring the wavelength dispersion and nonlinear coefficient of an optical fiber, method of manufacturing optical fibers, method of measuring wavelength-dispersion distribution, method of compensating for measurement errors, and method of specifying conditions of measurement

A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as an inexpensive light source producing a plurality of optical frequencies.

A method of simultaneously specifying the wavelength dispersion and nonlinear coefficient of an optical fiber. Pulsed probe light and pulsed pump light are first caused to enter an optical fiber to be measured. Then, the power oscillation of the back-scattered light of the probe light or idler light generated within the optical fiber is measured. Next, the instantaneous frequency of the measured power oscillation is obtained, and the dependency of the instantaneous frequency relative to the power oscillation of the pump light in a longitudinal direction of the optical fiber is obtained. Thereafter, a rate of change in the longitudinal direction between phase-mismatching conditions and nonlinear coefficient of the optical fiber is obtained from the dependency of the instantaneous frequency. And based on the rate of change, the longitudinal wavelength-dispersion distribution and longitudinal nonlinear-coefficient distribution of thee optical fiber are simultaneously specified.

An optical pulse generator comprises a comb-like dispersion profiled fiber formed into an optical loop mirror. The fiber may comprise three or more segments of fiber having alternating highly dispersive and highly nonlinear characteristics. The optical loop mirror construction splits an input pulse into two portions that propagate through the CDPF in opposite directions. The pulse portions are re-combined, and a compressed pulse with reduced noise is produced.

Optical pulse generator

A waveform converter for altering the waveform and optical spectrum of an optical signal may comprise a nonlinear element having a nonlinear effect on optical pulses, a dispersion element having a dispersion effect on optical pulses, and a wavelength selecting element configured to select spectral components in a desired wavelength region.

Optical pulse waveform conversion

A wavelength converting method and apparatus which converts wavelength division multiplexed (WDM) signal light, having a plurality of channels, by four-wave mixing the WDM signal light with at least one pump lightwave. Wavelength conversion of the WDM signal is accomplished without producing noise by FWM the WDM signal with a pump lightwave, wherein the pump lightwave frequency is separated from the WDM signal by an interval equal to or greater than the bandwidth of the WDM signal. Two pump lightwaves can be used instead of one, wherein one of the pump lightwaves has a frequency on one side of the bandwidth of the WDM signal, and the average frequency of the two pump lightwaves is on the other side of the WDM signal bandwidth.

Growing community of inventors

Tokyo, Japan

Misao Sakano