High conversion gain 10-GHz narrow-band photoreceiver with a flip-chip mounted 1.55 µm waveguide photodiode

The photoreceiver is a key component for microwave fiber optic links and optoelectronic generation of microwave and millimeter-wave in phased array antennas for radar systems. The narrow-band photoreceiver at 10 GHz, developed in this work, consists of a multimode waveguide photodiode grown on InP substrate and an electrical amplifier with GaAs pseudomorphic HEMTs (pHEMTs). The photoreceiver with a monolithically integrated surface illuminated photodiode has been investigated earlier. In this work, however, the photodiode is replaced by a flip-chip mounted waveguide photodiode. The waveguide photodiode has a three times higher responsivity (1 A/W) that that of a surface illuminated photodiode (0.34 A/W), which results in a considerably higher signal-to-noise ratio. This enables fabrication of high optoelectronic conversion gain and low noise photoreceivers.