Self-Pumping Wavelength Conversion for DPSK Signals and DQPSK Generation Through Four-Wave Mixing in Highly Nonlinear Optical Fiber

A novel scheme is proposed to achieve self-pumping wavelength conversion for two differential phase-shift keying (DPSK) signals at different wavelengths through four-wave mixing (FWM) effect in a highly nonlinear optical fiber. By changing the phase modulation depths to pi/2 for both of the DPSK signals, the two signals can be multiplexed to generate a differential quadrature phase-shift keying signal. The simulations and experimental results demonstrate the feasibility of phase manipulations for phase-shift keying signals through the FWM process