Impact of Nonlinearity Including Bleaching in p-i-n Photodetectors on RF-Modulated Electro-Optic Frequency Combs

Abstract

We use a drift-diffusion model that includes the effect of bleaching to study the impact of nonlinear distortion in a p-i-n photodetector (PD) on RF-modulated frequency combs. This work complements a similar study that we carried out for a modified uni-traveling carrier (MUTC) PD. We begin by using experimental responsivity data to develop an empirical model of the bleaching in a p-i-n PD when operating in pulsed mode. We then incorporate this model of bleaching into a drift-diffusion model. Next, we use this drift-diffusion model to determine the impact of nonlinearity on the second- and third-order intermodulation distortion products IMD2n and IMD3n as a function of the comb line number n. We then determine the corresponding output intercept points OIP2ₙ and OIP3ₙ and distortion-to-signal ratios ρ₂ₙ and ρ₃ₙ. In contrast to MUTC devices, we find that bleaching increases ρ₂ₙ and ρ₃ₙ at all comb line numbers. However, these distortion products change little as n increases, in contrast to MUTC devices where they grow rapidly as n increases.