Microwave nonlinearities in Ge/Si avalanche photodiodes having a gain-bandwidth product of 300 GHz

The nonlinearity of a 300 GHz gain bandwidth Separate Absorption Charge Multiplication (SACM) Ge/Si avalanche photodiode was examined experimentally for varying multiplication factors. The maximum second order dynamic range was 84.8 dB⋅Hz^½. The largest third order dynamic range was 101.5 dB⋅Hz^⅔.

1. Introduction

Avalanche photodiodes (APDs) are strong candidates for use in fiber optic receivers when input optical power is likely to be low because of their high sensitivity and adjustable gain. At telecommunications wavelengths, III-V APDs have traditionally been used, but they are impractical in very high speed applications because of their low gain-bandwidth product (-100 GHz) [1].