Proceedings PaperLiquid-crystal-based optical time-delay control system for wideband phased arrays
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We introduce a novel, time delay-based, transmit-receive mode, remotely located, optical control system for wide instantaneous bandwidth phased arrays. Time delays are achieved using a cascade of free-space and fiber-based optical delay lines using bulk imaging optics for low complexity, two dimensional, free-space optical interconnects. High channel isolation, low insertion loss optical switching between delayed and undelayed paths is based on polarization switching using the low cost nematic liquid crystal arrays and polarizing beam splitters. The system allows for noise reduction via spatial and polarization filtering. A dual- channel time-multiplexed system arrangement is used to implement the fast (e.g., 200 beams/s) radar scan rates using the several millisecond response time nematic liquid crystals.