DEVELOPMENT OF A MICROSECOND-PULSE NEODYMIUM LASER

THE TI:SAPPHIRE SOLID STATE LASER IS ONE OF THE MORE PROMISING SOURCES FOR SPACE-BASED DIAL SYSTEMS OPERATING IN THE NEAR-INFRARED REGION FROM 700-1000 NM. WHEN PUMPED BY APULSED, FREQUENCY-DOUBLED NEODYMIUM (ND) LASER, THE TI: SAPPHIRE LASER ACHIEVES NEARLY QUANTUM-LIMITED CONVERSION OF PUMP ENERGY INTO OUTPUT ENERGY. THE PULSE LENGTH OF CONVENTIONAL ND LASERS OPERATED IN THE FLASHLAMP-PUMPED, Q-SWITCHED MODE IS, HOWEVER, MUCH SHORTER THAN NECESSARY FOR PUMPING THE TI-SAPPHIRE SYSTEM. THE HIGH PEAK POWER ASSOCIATED WITH THE SHORT LENGTH LIMITS THE PUMP ENERGY DELIVERABLE PER UNIT AREA, BECAUSE OF OPTICAL DAMAGE TO THE SURFACE OF THE SAPPHAIRE CRYSTAL. THE INTENT OF THIS PROPOSAL IS TO BEGIN THE DEVELOPMENT OF ANENERGETIC (1 JOULE AND GREATER), FREQUENCY-DOUBLED ND LASER WITH A PULSE LENGTH ON THE ORDER OF 1-2 MICROSECONDS. IF A MICROSECOND PUMP SOURCE COULD BE DEVELOPED, THE ENERGY OUTPUT FROM A GIVEN APERATURE SIZE OF THE TI:SAPPHIRE GAIN MEDIUM COULD BE SIGNIFICANTLY INCREASED. THE PROPOSED PHASEI EFFORT WOULD INCLUDE A STUDY OF DIFFERENT TECNIQUES FOR GENERATING MICROSECOND-DURATION PULSES, AN EXPERIMENTAL IMPLEMENTATION OF ONE PARTICULAR TECHNIQUE AND AN ASSESSMENTOF SECOND-HARMONIC GENERATION EFFICIENCIES ATTAINABLE WITH KNOWN NONLINEAR CRYSTALS.