INGAAS DUAL PIN PHOTODIODE WITH MINIMIZED SERIES RESISTANCE FOR LOW-NOISE BALANCED RECEIVERS

Monolithically integrated planar front-illuminated InGaAs dual pin photodiodes (PD) with a series resistance less than 10-OMEGA have been fabricated for optical coherent receiver application. The PDs exhibit a very low dark current around 100 pA at -10 V, a high quantum efficiency (over 90%) and a 3 dB bandwidth of more than 10 GHz. The photosensitive area diameter is 50-mu-m2, which offers large fibre alignment tolerances. A 2.5 dB improvement of the average input noise current density of an optical front end comprising the dual pin PD and a tuned electronic preamplifier has been demonstrated.