A 2-CHANNEL OPTICAL DOWNCONVERTER FOR PHASE DETECTION

Experimental results for a two-channel optical downconverter link oper ating from 2 to 18 GHz are presented. Using low-noise preamplifiers re sults in a noise figure (NF) of 8.5-14 dB over the frequency range of 2 18 GHz. For the first time, relative phase measurements between opti cally downconverted signals have been performed. An in-phase/quadratur e phase-measurement technique indicates a phase precision of +/-2 degr ees with as little as -60 dBm radio frequency (RF) received power. Com paring the optical microwave downconverter to an electrical microwave downconverter in terms of phase detection reveals similar performance between the two systems.