Minghui YUAN^* and Lin CHEN

School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, No. 516, Jungong Road, Shanghai 200093, China

(Received January 25, 2010; Accepted May 24, 2010)

Performance deterioration induced by cross-phase modulation (XPM) in the basic nonlinear optical loop mirror (NOLM) switch unit in the digital optical communication system and analog microwave photonic communication system is studied by using the split-step Fourier method (SSFM) that can solve the coupled nonlinear Schrödinger equation (CNLSE). The simulation results show that the switching performance of basic NOLM unit is distorted by the XPM induced nonreciprocity when the splitting ratio of NOLM coupler f ≠ 0.5 and the distortion effect would be more serious with the increase of the working speed or the modulation bandwidth. In the digital optical communication system, the power transmission function of NOLM decreases in the range of 0< f <0.5 and increases in the range of 0.5< f<1. In the analog microwave photonic communication system, XPM induces the distortion of waveforms and the leak of side lobes. And the larger the modulation bandwidth is, the larger the leak of side lobes is.

Key words: cross-phase modulation (XPM), nonlinear optical loop mirror (NOLM), split-step Fourier method (SSFM), coupled nonlinear Schrödinger equation (CNLSE), nonreciprocity

^*E-mail address: minghui.yuan@163.com