Modeling of all-optical modulation format conversion from amplitude-shift keying to phase-shift keying using a vertical cavity quantum wells absorber

Abstract

A theoretical model for all-optical modulation format conversion from amplitude-shift keying (ASK) to phase-shift keying (PSK) has been proposed using a reflective vertical cavity semiconductor saturable absorber (R-VCSSA). The R-VCSSA is a nonlinear device. The phase response of the device has been studied numerically with different input intensities. It has been observed from the simulated result that a maximum phase of ± π / 2 with the reflected signal could be obtained by properly adjusting the input intensity. The conversion of an intensity-modulated return-to-zero (RZ) signal to a binary phase-shift keying signal has been analyzed based upon the simulated result. The pump signal is considered to be an intensity-modulated RZ signal with wavelength fixed at the cavity resonance of the R-VCSSA device, and a cavity-detuned continuous-wave source is used as a probe signal to carry out this operation. This device could be employed in all-optical future networks as an all-optical nonlinear signal converter for ASK to PSK conversion.