OPTIMAL LOOP LENGTH OF A NONLINEAR-OPTICAL LOOP MIRROR IN SWITCHING SOLITONS

The optimal loop length of a nonlinear optical loop mirror (NOLM) for switching solitons was investigated numerically for the case where the wavelengths of the control pulse and signal soliton straddle the disp ersion zero, In our analysis, the Raman effect is also included becaus e the wavelength difference between the control and signal pulses is w ithin the Raman gainband. It was found that the control pulse not only imposes phase shift on the copropagating signal, but also transfers p art of its energy to the signal. Furthermore, the broadening of the co ntrol pulse due to the combined effect of self-phase modulation and gr oup velocity dispersion increases the switching power of the control p ulse significantly, The broadening of the control pulse also introduce s more uniform phase shift to the signal, thus resulting in a higher s witching efficiency, Finally, our results show that the pulse distorti on is minimal if a loop length equivalent to one soliton period is emp loyed.