Development of Highly Nonlinear Fibers for Optical Signal Processing

Nonlinear optical phenomena occurring in optical fibers result in noise and wave- form distortion that are factors in signal degradation. It is therefore desirable that nonlinear phenomena in fibers used as the transmission path be reduced as much as possible. On the other hand consideration is being given to methods of optical signal processing that make use of the nonlinear phenomena occurring in the fibers. For example, by actively making use of such nonlinear phenomena as four-wave mixing (FWM) and self-phase modulation (SPM), it is possible to combine optical signals of multiple wavelengths to achieve wavelength conversion, pulse compression and the like 1)~4) . Such techniques for utilizing nonlinear phenomena are con- sidered promising in terms of the next generation of high-speed optical signal processing and long-haul optical transmission. A highly nonlinear optical fiber has been developed for wave- length conversion using FWM that has a dispersion slope of 0.02 ps/nm2/km or less. This fiber relaxes the dependence of the pump wavelength in wavelength conversion using FWM, broaden- ing the conversion bandwidth. We also report on a polarization-maintaining highly nonlinear fiber and a highly nonlinear fiber with reduced clad diameter. ABSTRACT