A novel optical nonlinearity in a semiconductor gain medium and its applications to wavelength filtering

The authors report on a novel NLO material and a new approach to an implementation of tunable, very narrow band, wavelength filtering and wavelength recognition based on the time response of an optical nonlinearity. The approach makes possible some important new optical devices for wavelength division multiplexing and is based on a new optical nonlinearity: a optically induced birefringence sensitive to the intensity and polarization of the optical signal. The proposed wavelength filtering can best be understood by considering a four-wave mixing (FWM) interaction in an NLO medium with a finite time response.<>