Compact optical sensor for detecting and tracking ocean-penetrating laser radar

The innovation proposed in this SBIR program is to develop a threat warning system against airborne laser radars in the blue-green transmission window. The proposed sensor system characterizes a sample through wavlelength, temporal, and spatial (theta fi) characteristics of the backscattered and source emission signals, enabling the air-borne laser radar to be identitied and tracked. The sensors to be demonstrated in this program are based on volume holographic Bragg-gratings in photorefractive crystals. The rotationally-tuned Bragg-grating has the potential of high throughput, high background rejection, and very high chromatic resolving power, making it a promising candidate for detecting the existence of a laser radar transmitter. It is expected that the volume holographic gratings should offer two orders of magnitude increase in the detection efficiency over conventional spectroscopic instruments of similar size. The innovations are directed toward improving the sensitivity, and reducing the system's mass, volume, alignment difficulties, and cost over existing solutions.