DEVELOPMENT OF SYSTEMS FOR CONTINUOUS TUNING AND SINGLE MODE OPERATION OF SOLID STATE LASERS

NARROW BAND, STABLE, SINGLE LONGITUDINAL MODE CONTINUOUSLY TUNABLE SOLID STATE LASERS ARE REQUIRED FOR A NUMBER OF APPLICATIONS SUCH AS LIDARS, HIGH RESOLUTION SPECTROSCOPY, ETC. IT IS PROPOSED TO DEVELOP A TUNABLE, NARROW BAND ( 0.001 CM(-1), STABLLE ( 0.0005 CM(-1) ALEXANDRITE LASER BY INJECTION SEEDING THE LASER OSCILLATOR WITH A STABLE TUNABLE DIODE LASER. THE OUTPUT FREQUENCY OF THE DIODE LASER WILL BE PRECISELY TUNED AND CONTROLLED BY USING A DIGITAL WAVEMETER AND FEEDBACK MECHANISM. A LARGE ARRAY DETECTOR AND A SPECIFIC ALGORITHM WILL BE USED TO PROCESSES THE WAVEMETER OUTPUT, WHICH TOGETHER WITH A STABLE FREQUENCY REFERENCE WILL ACHIEVE THE REQUIRED ACCURACY. A COMMERCIALLY AVAILABLE ALEXANDRITE LASER WILL BE USED FOR THIS SYSTEM. HOWEVER, A RING LASER CONFIGURATION IS PROPOSED FOR INJECTION SEEDING. THE DIODE LASER BEAM WILL BE INJECTED THROUGH AN OPTICAL ISOLATOR INTO THE RING IN THE DIRECTION OPPOSITE TO THAT OF THE LASER OUTPUT. THE LENGTH OF THE LASER RESONATOR CAVITY WILL BE PRECISELY CONTROLLED DYNAMICALLY WITH AN ACTIVE ELEMENT TO MATCH THE RESONATOR MODE FREQUENCY WITH THE INJECTION SEEDING FREQUENCY. TRUE SINGLE LONGITUDINAL MODE OPERATION OF THE LASER WILL BE ACHIEVED BY USING A HIGHRESOLUTION WAVEMETER INTERFACED WITH THE ACTIVE CAVITY ELEMENT OF THE LASER RESONATOR AS THE FEEDBACK ELEMENT.