Analysis of Switching Characteristics of a NOLM Demultiplexer with Signal-Control Pulse Walk-off and GVD Effects

Abstract

The switching characteristics of a nonlinear optical loop mirror (NOLM) demultiplexer are analyzed with the emphasis on signal-control pulse walk-off and group velocity dispersion (GVD) effects by using the split-step Fourier method. It is shown that the walk-off can broaden the switching window of NOLM, make the window profile deviate its central position, and decrease its switching efficiency. Overmuch walk-off is detrimental because it can broaden the switching window considerably and lead to crosstalk of neighboring channel signals to the demultiplexed signal. A new solution scheme, which is adjusting the initial time delay between signal pulse and control pulse and the peak power of control pulse, is proposed to overcome this adverse effect. Large GVD is harmful to a NOLM demultiplexer, for this reason, the NOLM demultiplexer should be operated near the zero-dispersion wavelength of the fiber.