Small-junction-area GaInAs/InP <i>pin</i> photodiode with monolithic microlens

Abstract

We report on a back-illuminated GaInAs/InP pin photodiode with a monolithic microlens that we have fabricated. The photodiode has both an ultrabroad bandwidth of 18 GHz and a high quantum efficiency of about 84%. It achieves this by using a small pin junction area while maintaining a large fibre alignment tolerance by incorporating an InP microlens. The photodiode capacitance was 20 fF for a junction diameter of approximately 15μm.