Theoretic analysis of pulse shaping by using nonlinear optical loop mirror based on crystal fiber

A nonlinear optical loop mirror (NOLM) based on photonic crystal fiber (PCF) is used for optical pulse shaping. The transmission of optical pulses in the fiber loop can be described by the nonlinear Schrodinger equations. The crossing phase modulation (XPM) effect which happens between signal pulse and control pulse in NOLM is used for pulse shaping. The theory of XPM effect in NOLM is analyzed theoretically and the process of pulse shaping is simulated. For the input Super-Gaussian signal pulses, it can be found that the pulse can be shaped from flat to sharp by the compression effect. For the input Hyperbolic-Secant signal pulses, it can be found that the pedestal from the compressed pulse can be suppressed by the NOLM. Due to the characteristics of PCF, especially high nonlinear properties, the high quality shaped pulses can be got. Compare with the self phase modulation (SPM) effect for optical pulse shaping, it is shown that the input pulse with low power itself can be shaped and the shaping of the input pulse can be controlled by the control pulse. Based on the analysis of the result, proper parameters and the crystal fiber of the NOLM will be selected.