HIGHLY SENSITIVE FIBER OPTIC ACOUSTIC POINT SENSORS

OUR PROPOSAL EFFORT DEFINES AN APPROACH TO DEVELOP A HIGHLY SENSITIVE, HYDROACOUSTIC, FIBER-OPTIC POINT SENSOR UTILIZING A LOW FINESSE FABRY-PEROT STRUCTURE AS THE ACOUSTIC TRANSDUCER. THE DESIGN CONCEPT EMBODYING OUR APPROACH ALLOWS HIGH SENSITIVITY, THE ABILITY TO OPERATE AT HYDROSTATIC DEPTHS EXPERIENCED BY MILITARY UNDERWATER VEHICLES,AND UNIQUE DIGITAL DEMODULATION SCHEME CAPABLE OF SUPPORTING MANY REMOTE SENSORS WITH A SINGLE LASER AND RECEIVER/DEMODULATOR. WE PROPOSE THAT THIS TYPE OF FIBER OPTIC HYDROPHONE CAN BE IMPLEMENTED IN ANARRAY CONFIGURATION WITH A COMPLETELY PASSIVE (NON-ELECTRIC) WET END, DRAMATICALLY REDUCING THE COMPLEXITY AND COST OF THE WET END PROCESSING AND TELEMETERING ELECTRONICS USED IN CONVENTIONAL ARRAY SYSTEMS. WE FURTHER PROPOSE THAT THE DYNAMIC RANGE AND FREQUENCY RESPONSECAPABILITIES OF THE ALL FIBER POINT SENSOR SYSTEM WILL SURPASS THOSEOF CONVENTIONAL TECHNOLOGY WHEN USED IN CONJUNCTION WITH THE DIGITAL DEMODULATION SYSTEM. DURING PHASE I, WE PROPOSE TO IDENTIFY THE SENSOR DESIGN PARAMETERS AND HARDWARE COMPONENTS BEST SUITED TO MEET THE MISSION AND COST REQUIREMENTS FOR THE UNDERWATER VEHICLE. WE WILL DEMONSTRATE THIS DESIGN BY FABRICATING A FEW "SINGLE ELEMENT" SENSORS WITH LASER AND DEMODULATION ELECTRONICS. VERIFICATION OF HYDRO-ACOUSTIC PERFORMANCE WILL BE ACCOMPLISHED BY CONDUCTING LABORATORY ACOUSTIC EXPERIMENTS.