GROWTH OF ND:YV04 CRYSTALS FOR LASER TECHNOLOGY

SPACE COMMUNICATIONS AT OPTICAL FREQUENCIES DEMAND THE DEVELOPMENT OF LASER CRYSTALS THAT EXHIBIT HIGH POWER-CONVERSION EFFICIENCY. GROWTH OF ND:YVO4 SINGLE CRYSTALS BY AN INNOVATIVE, LASER PEDESTAL GROWTH METHOD WILL BE EXPLORED. EARLIER PUBLISHED WORK HAS CLEARLY REVEALED THAT THESE CRYSTALS EXHIBIT A VERY HIGH SLOPE EFFICIENCY, LESS THAN 50 PERCENT OPTICAL EFFICIENCY, AND 12 PERCENT ELECTRICAL-TO-OPTICAL CONVERSION EFFICIENCY. DUE TO THE HIGH MELTING POINT OF YTTRIUM VANADATE (ABOUT 1825 DEGREES CENTIGRADE), CONVENTIONAL CRYSTAL-GROWTH TECHNIQUES YIELD CRYSTALS WITH NUMEROUS DEFECTS. THE INNOVATIVE TECHNIQUE USED IN THIS PROJECT INVOLVES GROWING THESE CRYSTALS WITH A LASER PEDESTAL GROWTH METHOD IN WHICH ONLY A SMALL SECTION OF THE MATERIAL IS MELTED WITH A CARBON DIOXIDE LASER SOURCE COUPLED WITH A FEW MIRRORS TO FOCUS THE BEAN AT THE CRYSTAL-LIQUID INTERFACE. THE CHIEF ADVANTAGES OF THIS METHOD ARE THAT THE GROWTH PROCESS IS RELATIVELY FAST AND THAT THE CRYSTALS ARE GROWN WITHOUT ANY CONTAINER. AS A RESULT, THE CRYSTALS ARE FREE OF ANY CONTAMINATION. THE GOAL OF PHASE I WILL BE TO ESTABLISH THE OPTIMUM CONDITIONS FOR THE GROWTH OF THESE CRYSTALS IN RELATIVELY SMALL SIZE. DURING PHASE II, EXTENSIVE WORK WOULD BE UNDERTAKEN TO GROW LARGE CRYSTALS AND CHARACTERIZE THEM THOROUGHLY. SPACE COMMUNICATIONS AT OPTICAL FREQUENCIES DEMAND THE DEVELOPMENT OF LASER CRYSTALS THAT EXHIBIT HIGH POWER-CONVERSION EFFICIENCY. GROWTH OF ND:YVO4 SINGLE CRYSTALS BY AN INNOVATIVE, LASER PEDESTAL GROWTH METHOD WILL BE EXPLORED. EARLIER PUBLISHED WORK HAS CLEARLY REVEALED THAT THESE CRYSTALS EXHIBIT A VERY HIGH SLOPE EFFICIENCY, LESS THAN 50 PERCENT OPTICAL EFFICIENCY, AND 12 PERCENT ELECTRICAL-TO-OPTICAL CONVERSION EFFICIENCY. DUE TO THE HIGH MELTING POINT OF YTTRIUM VANADATE (ABOUT 1825 DEGREES CENTIGRADE), CONVENTIONAL CRYSTAL-GROWTH TECHNIQUES YIELD CRYSTALS WITH NUMEROUS DEFECTS. THE INNOVATIVE TECHNIQUE USED IN THIS PROJECT INVOLVES GROWING THESE CRYSTALS WITH A LASER PEDESTAL GROWTH METHOD IN WHICH ONLY A SMALL SECTION OF THE MATERIAL IS MELTED WITH A CARBON DIOXIDE LASER SOURCE COUPLED WITH A FEW MIRRORS TO FOCUS THE BEAN AT THE CRYSTAL-LIQUID INTERFACE. THE CHIEF ADVANTAGES OF THIS METHOD ARE THAT THE GROWTH PROCESS IS RELATIVELY FAST AND THAT THE CRYSTALS ARE GROWN WITHOUT ANY CONTAINER. AS A RESULT, THE CRYSTALS ARE FREE OF ANY CONTAMINATION. THE GOAL OF PHASE I WILL BE TO ESTABLISH THE OPTIMUM CONDITIONS FOR THE GROWTH OF THESE CRYSTALS IN RELATIVELY SMALL SIZE. DURING PHASE II, EXTENSIVE WORK WOULD BE UNDERTAKEN TO GROW LARGE CRYSTALS AND CHARACTERIZE THEM THOROUGHLY.