HIGHLY SENSITIVE QUANTUM DETECTOR IN THE 10-50 MICRON REGION FABRICATED WITH HIGH TC BCSCO BY PLASMA ASSISTED LASER DEPOSITION

IN THE PROPOSED PROGRAM, FOR THE FIRST TIME, FEASIBILITY OF DEVELOPING AND CHARACTERIZING A HIGHLY SENSITIVE AND HIGH SPEED QUANTUM DETECTOR IN THE 10-50 MICRO WAVELENGTH REGION USING A SUPERCONDUCTING SSS TYPE WEAK LINK OF BI-CA-SR-CU-O, IS EXAMINED. THE DETECTION PRINCIPAL IS BASED ONT HE FACT THAT THE ABSORED INFRARED RADIATION REDUCES THE ENERGY GAP OF THE SUPERCONDUCTOR, MODIFYING THE CURRENT--VOLTAGE CHARACTERISTICS OF JOSEPHSON JUNCTION WHICH CAN SERVE AS A SUEFUL DETECTOR OUTPUT. RECENTLY, IN A PRELIMINARY EXPERIMENT, WE HAVE OBSERVED FOR THE FIRST TIME, NOT ONLY A SLOW BOLOMETRIC RESPONSE BUT ALSO A FAST NON-THERMAL QUNATUM RESPONSE DUE TO COOPER PAIR BREAKING AND QUASI-PARTICLES GENERATION IN YBACUO FILM SUBJECTED TO PULSED 532 NM LASER. IN THE PRESENT WORK, PRECISELY CONTROLLED THIN FILM OF BI-CA-SR-CU-O WILL BE DEPOSITED ON A SUITABLE SUBSTRATE BY PLASMA ASSISTED LASER DEPOSITION USING 265 NM UV LASER AT 10 HZ. SUBSEQUENT TO DEPOSITION, SUPERCONDUCTING WEAK LINK SSS TYPE JOSEPHSON JUNCTION WILL BE FABRICATED BY PATTERNING THESE FILMS WITH 532 NM VISIBLE LASER AT 1 KHZ. FOR DETECTION, INFRARED RADIATION FROM CO2 LASER AT 10.6 MICRON WILL BE MODULATED AND GUIDED THROUGH AN OPTICAL FIBER TO THE DETECTOR. IN THE PHASE I, NON-EQUILIBRIUM (QUANTUM) RESPONSE OF THE DETECTOR AT 10.6 MICRON AND THE TEMPERATURE DEPENDENCE OF THE RESPONSE WILL BE STUDIED. THE RESPONSIVITY OF THE DETECTOR IS ESTIMATED TO BE \ 10(4) V/W, WHICH IS SEVERAL ORDERS OF MAGNITUDE HIGHER THAN PRESENTLY AVAILABLE QUANTUM DETECTORS. IN PHASE II, WAVELENGTH DEPENDENCE OF THE RESPONSE IN THE 10-50 MICRON REGION, HIGH FREQUENCY RESPONSE, AND THE TEMPERATURE DEPENDENCE OF THE RESPONSIVE TIME WILL BE INVESTIGATED.