HIGHLY SENSITIVE INFRARED DETECTOR FABRICATED WITH THIN FILM OF HIGH TC Y-BA-CUO SUPERCONDUCTOR USING PULSED EXCIMER LASER

IN THE PROPOSED WORK, FEASIBILITY OF DEVELOPING A HIGHLY SENSITIVE AND HIGH SPEED OPTICAL DETECTOR IN THE INFRARED REGION USING A SUPERCONDUCTING WEAK LINK FABRICATED BY LASER INDUCED DEPOSITION OF Y-BA-CU-O THIN FILMS, IS EXAMIED. THE DETECTION PRINCIPLE IS BASED ON THE FACT THAT INCIDENT INFRARED RADIATION PRODUCES A VOLTAGE ACROSS THE JOSEPHSON JUNCTION WHICH CAN SERVE AS A USEFUL DETECTOR OUTPUT. IN THE PRESENT WORK, BULK SUPERCONDUCTOR SAMPLES OF Y-BA-CU-OWILL BE PREPARED BY SOLID STATE REACTION METHOD. THIN SUPERCONDUCTING FILM ON A SUITABLE SUBSTRATE WILL BE PREPARED BY LASER INDUCED DEPOSITION TECHNIQUE USING PULSED EXCIMER LASER. IN THIS TECHNIQUE, THE U.V. LASER REMOVES MOLECULES (PHOTO-ABLATION) FROM THE SUPERCONDUCTOR TARGET WHICH ARE SUBSEQUENTLY DEPOSITED ON MGO SUBSTRATE WHICH HAS BEEN CLEAVED TO FORM A WEAK LINK. A MAJOR ADVANTAGE OF THE PROPOSED TECHNIQUE IS THAT DUE TO EXCELLENT SPATIAL QUALITY AND SHORT WAVELENGTH (O.28 MICRO) OF THE LASER, IT PROVIDES A PRECISE CONTROL OVER THE DEPOSITION PROCESS WITH SUBMICRON RESOLUTION. FOR DETECTION, INFRARED SIGNALS WILL BE MODULATED AND GUIDED THROUGH A OPTICAL FIBER TO THE DETECTOR. DETECTOR PERFORMANCE IN TERMS OF, RESPONSIVITY AND DYNAMIC RANGE, IN THE SPECTRAL REGION OF 1-10 MICRON WILL BE EVALUATED.