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E. H. Young, NEOS Technologies Inc., Melbourne, FL 32904ABSTRACTThe axial separation distance between an intracavity resonant Raman-Nath acousto-optic modulator and the secondary mirror of an unstable resonator of a TE CO2 laser hasstrong effects on the mode-lockng efficiency. Experimental measurements showed that themode-locker laser pulse width was a periodic function of the separation distance with aperiod of about 18 mm. Preliminary simple analyses using a two-beam interference modelyield a periodic sine-squared acousto-optic diffraction intensity distribution as a function ofseparation distance with the mode-locked pulse width varying as the inverse of sine to thefourth power of the diffraction intensity. The observed pulse width was in good agreementwith the calculated value using the above interference theory.Keywords: Mode-Locking, Optical Interference, CO2 laser, Raman-Nath AO modulator.2. INTRODUCTIONA very efficient Raman-Nath mode-locker1 is used for generating nanosecond mode-locked pulses in the Eield jadar emonstrator, FLD, long-range imaging CO2 laser radar |
