A folded-path GaAs travelling-wave modulator for phased array receivers

We have designed and demonstrated a DC-18 GHz GaAs travelling-wave modulator suitable for a complex multi-beam phased-array antenna receive system. The defining feature of the design is on-chip optical path-folding to enable the needed dense packing of the Rx modules with RF input at one end and optical interrogation from the other. Chip loss is below 6 dB. The optical S/sub 11/ is low and dominated by the AR-coating of the optical facet.