NEW FOUR-LEVEL ALL-SOLID-STATE LASER SOURCE WITHIN THE 1.5-4 UM RANGE.

REMOTE ATMOSPHERIC SENSING AND SPACE BASED LIDAR SYSTEMS REQUIRE SOURCES IN THE NEAR INFRARED. SOURCES UNDER CURRENTDEVELOPMENT ARE QUASI-THREE LEVEL LASERS, SUCH AS CR:ER:YAG (1.6 UM) AND TM:HO:YAG (2.1 UM). OPERATION OF QUASI-THREE LEVEL LASERS IS TEMPERATURE DEPENDENT AND SUCH DEVICES HAVE INCREASED THRESHOLDS AND REDUCED EFFICIENCIES AT ROOM TEMPERATURE. WE PROPOSE A NEW FOUR-LEVEL SOLID-STATE LASER BASED ON A PREVIOUSLY UNEXPLORED COMBINATION OF RARE-EARTH IONS IN A GARNET HOST. WE WILL GROW THE CO-DOPED CRYSTAL, EXAMINE ITS LASER POTENTIAL BY SPECTROSCOPY AND PERFORM A LASER PUMPED LASER EXPERIMENT. THE CO-DOPED SYSTEM WILL BE PUMPED BY VISIBLE SOURCES FOR INITIAL INVESTIGATIONS BUT CAN BE PUMPED BY GAA1AS DIODES IN THE 750-850 NM RANGE FOR SPACE BASED APPLICATIONS. THE LASING ION HAS FOUR EMISSION BANDS, NOT TERMINATING IN THE GROUND STATE, FROM 1.5 TO 4 UM INCLUDING A TRANSITION IN THE 'EYE SAFE' (1.4-1.85 UM) REGIME. THIS LASER COULD BE A DIRECT SOURCE FOR OPTICAL SENSING IN THE NIR AS WELL AS BEING AN EFFICIENT PUMP SOURCE FOR NONLINEAR TUNABLE DEVICES SUCH AS OPTICAL PARAMETRIC OSCILLATORS. THE EYE SAFE TRANSITION COULD YIELD A PARTICULARLY IMPORTANT SOURCE FOR ATMOSPHERIC WIND, CLOUD HEIGHT AND GROUND ELEVATION STUDIES.