FREQUENCY STABILIZATION IN PULSED LASER WAVEFORMS

A DESIGN PHASE PROGRAM IS PROPOSED FOR THE DEVELOPMENT OF A PROCESS AND EQUIPMENT FOR USE IN FREQUENCY CONTROL OF PULSED LASERS TO ACHIEVE VERY HIGH FREQUENCY STABILITY ( 1 IN 10 TO THE 10TH POWER OR 10 TO THE 11TH POWER). THERE EXISTS A VARIETY OF IMPORTANT LASER RADAR APPLICATIONS FOR WHICH ENERGETIC LASER PULSES ARE NEEDED AT A FREQUENCY STABILITY AT THIS LEVEL. THE EXISTING METHOD TO ACHIEVE SUCH HIGH STABILITY CONSISTS OF A MOPA CONFIGURATION IN WHICH THE OUTPUT OF A STABLE CW LASER IS AMPLIFIED IN A LARGE PULSED POWER AMPLIFIER BANK. THIS APPROACH SUFFERS FROM TWO MAJOR DRAWBACKS: LARGE SIZE AND INABILITY TO RETAIN THE FREQUENCY STABILITY IN THE PRESENCE OF THE INTENSE ACOUSTICS AND MICROPHONICS ENVIRONMENT IN AN AIRCRAFT. LSI'S PROPOSED "V"-PROCESSOR FOR PULSED LASER FREQUENCY CONTROL IS BASED ON AN ADAPTIVE PROCESS. THE "V"-PROCESSOR SENSES THE FLUCTATIONS OF AN INCIDENT LASER PULSE AT ITS INPUT REFERENCED AGAINST A STABLE OPTICAL CLOCK. THE PROCESSOR REMOVES THE FLUCTUATIONS FROM THE SAME PULSE ELECTRO-OPTICALLY AT A DELAYED TIME. IT ALSO ANCHORS THE PULSE FREQUENCY AT THE CLOCK FREQUENCY. THE PROPOSED DESIGN-PHASE WILL FORMULATE A HARDWARE DEVELOPMENT PROGRAM TO BE IMPLEMENTED IN PHASE II. THE HARDWARE DEVELOPMENT WILL INCLUDE A COMPLETE "V"-PROCESSOR.