The Furukawa Electric Co., Ltd.

Osamu Aso

Masateru Tadakuma

Shu Namiki

Misao Sakano

Takeshi Nakajima

Katsutoshi Takahashi

Yu Mimura

Yoshihiro Emori

Yuichiro Irie

Kouki Sato

Shunichi Matsushita

Atsushi Oguri

Koji Igarashi

Hijiri Nimura

Kazuyo Mizuno

Shunichi Matushita

Haruki Ogoshi

Shoichi Ozawa

Shyoichi Ozawa

Ikuo Ohta

Isamu Ohshima

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

The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines. Further, the present invention provides a light source comprising a plurality of continuous light sources of which at least one oscillates in a multimode; a multiplexer for multiplexing output light from the continuous light sources; and a nonlinear phenomenon producer for producing a nonlinear phenomenon on output light from the multiplexer so as to suppress SBS (Stimulated Brillouin Scattering).

Light source in optical transmission system, waveform shaper, optical pulse train generator and optical reproduction system

Light source in optical transmission system, waveform shaper, optical pulse train generator, and optical reproduction system

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

The present invention provides a method for generating four-wave mixing to obtain idler light with high efficiency, in which the range of lengths of an optical fiber is appropriately set, and probe light and pumping light, having different frequencies, are launched into the optical fiber. When the nonlinear coefficient of the optical fiber, the loss per unit distance, and the wavelength and intensity of the probe light and pumping light are set to certain values, the idler light conversion efficiency at the output end of the optical fiber is a periodic function of an optical fiber having a maximal value and a minimal value. The maximum length of the optical fiber to be used to obtain four-wave mixing is set to be equal to or less than the length Lmax (Lmax=Lm+&#x394;L) which is given by adding the length of the optical fiber Lm, at which the idler light conversion efficiency takes on the first maximal value in the aforementioned periodic function and distance &#x394;L or 10% of L.

Method for efficient four-wave mixing generation and short pulse generation equipment using the method

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 wavelength converter using difference frequency generation (DFG) is disclosed. In one embodiment, the wavelength converter comprises (a) a first optical filter configured to filter out one or more lightwaves requiring wavelength conversion from wavelength-division multiplexed (WDM) lightwaves, and (b) a broadband multi-channel simultaneous wavelength conversion portion comprising a pump source that generates pump light for use in the process of the DFG, a first optical combiner for combining said pump light with said filtered lightwaves, a high non-linear medium configured to generate wavelength converted lightwaves from said filtered lightwaves using the DFG, and a second optical filter for filtering said wavelength converted from said filtered lightwaves.

Wavelength converter and wavelength division multiplexing transmission method using the same

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.

Method and apparatus for wavelength conversion

Solely lightwaves required to be wavelength converted are filtered out from the input broadband WDM lightwaves and are wavelength converted by use of FWM. Not only the broadband simultaneous wavelength conversion that is studied by many researchers, but also more flexible, sub-band wavelength conversion is realized. Frequency interval of the input WDM lightwaves is broadened or reduced in comparison of the frequency interval of the WDM lightwaves inputted to the wavelength converter. The frequency interval variation techniques using the wavelength converter, it can be realized to transfer from a transmission line less influenced by inter-channel crosstalk due to FWM to the different transmission lines strongly influenced by inter-channel crosstalk due to FWM, and vice versa.

Wavelength converter and wavelength division multiplexing transmission method using same

The present invention provides a method for generating four-wave mixing to obtain idler light with high efficiency, in which the range of lengths of an optical fiber is appropriately set, and probe light and pumping light, having different frequencies, are launched into the optical fiber. When the nonlinear coefficient of the optical fiber, the loss per unit distance, and the wavelength and intensity of the probe light and pumping light are set to certain values, the idler light conversion efficiency at the output end of the optical fiber is a periodic function with respect to optical fiber length having a maximal value and a minimal value. The maximum length of the optical fiber to be used to obtain four-wave mixing is set to be equal to or less than the length Lmax (Lmax&equals;Lm&plus;&Dgr;L) which is given by adding the length of the optical fiber Lm, at which the idler light conversion efficiency takes on the first maximal value in the aforementioned periodic function and distance &Dgr;L or 10% of Lm.

Growing community of inventors

Tokyo, Japan

Osamu Aso