AN ALL-SOLID-STATE LASER SOURCE FOR PRODUCTION OF POLARIZED ELECTRONS

BEAMS OF POLARIZED ELECTRONS ARE REQUIRED FOR NUCLEAR PHYSICS EXPERIMENTS PLANNED FOR THE CONTINUOUS ELECTRON BEAM ACCELERATOR FACILITY (CEBAF) NEARING COMPLETION. POLARIZED ELECTRONS CAN BE GENERATED BY ILLUMINATING SPECIALLY PREPARED SEMICONDUCTOR PHOTOCATHODES WITH LIGHT OF WAVELENGTH AROUND 800 NM. THE FIRST GENERATION LASER SOURCE TO BE USED FOR THE PRODUCTION OF POLARIZED ELECTRONS AT CEBAF WILL BE CONTINOUS WAVE (CW) TITANIUM-DOPED SAPPHIRE LASER PUMPED BY AN ARGON-ION LASER. ALTHOUGH THIS CONVENTIONAL LASER SYSTEM WILL MEET THE BASIC NEEDS OF CEBAF, IT HAS LESS THAN OPTIMAL LIFETIME AND OPERATIONAL STABILITY. THIS PHASE I PROJECT IS INVESTIGATING THE FEASIBILITY OF AN ALL-SOLID-STATE LASER SYSTEM THAT WOULD BE USED AS A SECOND-GENERATION SOURCE FOR CEBAF. THE PLANNED SYSTEM USES DIODE LASER ARRAYS TO OPTICALLY PUMP A NEODYMIUM-DOPED LASER THAT IS FREQUENCY DOUBLED AND THEN USED TO PUMP A TITANIUM:SAPPHIRE LASER TO PRODUCE TUNABLE OUTPUT IN THE NEAR INFRARED REGION AROUND 800 NM. THE TITANIUM:SAPPHIRE LASER WILL PREFERABLY BE MODE LOCKED OR ELSE CW. THIS ALL-SOLID-STATE LASER SYSTEM IS PLANNED TO BE COMPACT, EFFICIENT, LONG LIVED, AND RELIABLE. PHASE II WILL ENTAIL DEVELOPMENT OF A LASER SYSTEM WITH THE REQUIRED PERFORMANCE.