High-speed all-optical thresholding via carrier lifetime tunability

We theoretically study the effect of free-carrier lifetime on processing speed and strength of nonlinearity, pertaining to our all-optical thresholder. We find that optimal device performance necessitates tuning lifetime while optimizing for both speed and nonlinearity. We also experimentally demonstrate device processing speed improvement from 400 Mbps to 2.5 Gbps by incorporating PN-junction mediated free-carrier lifetime tuning mechanism. Our study on the significance of free-carrier lifetime is universally applicable to any optical signal processing system reliant on silicon photonic nonlinearities.