Monolithic integration of an InP based polarization diversity heterodyne photoreceiver with electrooptic adjustability

In this paper we describe the monolithic integration, in the InP/InGaAsP material system, of a polarization diversity optical heterodyne receiver. The study concerns different components which are part of the device: polarization splitters, adjustable 3 dB TE and TM directional couplers, waveguide integration with PIN photodiodes, modal tapers, and JFET´s. All these devices are developed in a compatible integration approach, as building blocks of the overall device. Eventfully, two circuit demonstrators-a polarization-diversity optical circuit integrated with two balanced-PIN pairs and a coupler integrated with a balanced-PIN pair and JFET amplifier-are presented. These two circuits show very good characteristics in terms of internal loss, rejection ratio, electrical bandwidth, and input noise, similar to hybrid circuits. This work paves the way for the use of complex integrated photoreceivers for system application