Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 an 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 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.

Abstract: 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.

Abstract: A superconducting accelerating tube which is constructed by welding and connecting a plurality of half cells (11) formed of superconductor material in a dish form having a substantially constant wall thickness of the material, and having a small-diameter portion (11a) and a large-diameter portion (11b) and in which the shell diameter periodically varies. The half cells (11) are welded together via ring-shaped connecting members (12) formed of superconducting material and disposed between the small-diameter portions (11a), and the half cell (11) and connecting member (12) are formed of Nb.

Abstract: A superconducting accelerating tube which is constructed in a manner such that a plurality of components, formed of a superconducting material and individually having peripheral end portions adapted to be butted to one another, are butted to one another at the peripheral end portions, and the butting portions butted to one another are welded together. In the superconducting accelerating tube according to the present invention, the butting portions are welded by means of a laser beam, and the laser beam is applied to the butting portions so that the components are laser-welded to one another. Preferably, the accelerating tube is designed so that at least only the respective inner surfaces of the butting portions are laser-welded, and the depth of welding is not greater than half the thickness of the superconducting material and not smaller than 150 .mu.m.