Theoretical analysis on polarization deviation and switch window optimization in nonlinear optical loop mirror demultiplexer

This paper investigates theoretically two of the dominant issues on a nonlinear optical loop mirror (NOLM) demultiplexer: the sensibility to the polarization deviation between signal and control pulses and the optimization of the switch window width. The complete nonlinear Schrodinger equations concerning the different states of polarization between signal and control lights are firstly established to study the impact of the polarization deviation on the demultiplexed signal. Considering simultaneously the channel crosstalk and the timing jitter between signal and control pulses, the switch window width of NOLM is optimized to achieve the best demultiplexing performance. The theoretical analysis shows that the polarization deviation has to be controlled less than 20° within the bit error rate (BER) of 10^-9 s. The optimal amount of the pulse walkoff is a little less than half of the slot width of the OTDM system