All-optical 2R regeneration with contrast enhancement in a reflective vertical cavity quantum-wells saturable absorber

Round-trip nonlinear phase-shift of an input signal due to optically induced thermal effects and saturable index change in a low intensity resonant reflective vertical cavity semiconductor (quantum wells) saturable absorber (VCSSA) is investigated theoretically for 2R (re-amplification and re-shaping) regeneration. Calculations are carried out for a high contrast switching system to find the optimum value of parameters such as energy time filling factor (FF) of the input pump signal, top mirror reflectivity (Rt) of the Fabry-Pérot cavity and wavelength detuning from the low intensity resonant wavelength of the Fabry-Pérot cavity. It is observed that the optimum contrasts are almost the same for a wavelength tuning range as large as 8 nm around the low intensity resonance wavelength of the InGaAs/InP quantum-wells-based VCSSA with Rt of 0.72 and FF of 0.10. The simulation shows that the required average input power is minimal for high contrast 2R regeneration when operated in the short wavelength side.