Fast Optical Limiters (OL) with Enhanced Dynamic Range

Current fielded sensor protection is limited to fixed wavelength filters. Broadband filters designed to circumvent multi-wavelength laser threats are plagued by low transmittance, which degrades the sensitivity and performance of the sensor. Future warfighter threats include frequency agile lasers and thus have the potential of defeating fixed filters. Self-activating (passive) devices where protection is activated by the incoming radiation (optical limiting) are the best approach to counter frequency agile and short pulse laser threats. In our Phase I effort we demonstrated through experiment and simulations that the phase change material VO2 can be thermally managed to defeat future laser threats across the IR wavelength regime. In Phase II we will design, fabricate and test our optical limiter device and system concepts based on composite materials containing VO2 phase change material in the form of films and nanostructures embedded in a host. The novel optical limiter devices have large angular acceptance, large band width, nanosecond response times, high laser damage threshold, and short reset times. The materials are grown using physical deposition processes and devices could be made over large areas. The compact devices can be integrated into existing EO/IR sensors against laser threats.