An efficient waveguide photodetector fabricated in an InP-based amplifier layer stack

This article describes the fabrication and characterization of a waveguide pin-photodetector(WGPD) based on butt-joint integration of a passive waveguide and photodetector.The WGPD is fabricated in a layer stack that is designed to be used for an optical amplifier,which now acts as a detector by reversely biasing the pin-diode. The device isfabricated in active-passive material with a technology that uses two epitaxial regrowthsteps. The static and high-frequency behavior of the photodetector are characterized anddemonstrate a very low dark current of 20 nA at -4 V and an internal efficiency of morethan 65% for a 60μm long device at -5V bias voltage around a wavelength of 1.5μm. Theoutput reflection coefficient shows more than 20GHz bandwidth for a 70μm long device