The Influence Of Diffraction Efficiency On The Output Characteristics Of Multi-Transverse Mode Laser In A-O Q-switched DPL

The diffraction characteristics of the acousto-optic Q-switch has effect on theoutput pulse characteristics of each transverse mode laser in the high-powerDPL(diode pumped solid-state laser).This paper is mainly about the influence of thedivergence angle of ultrasound on the acousto-optic diffraction efficiency of eachtransverse mode during the Q-switched process, and the influences of different changerates of acousto-optic diffraction efficiency and acousto-optic diffraction efficiency ofeach transverse mode on the output pulse characteristics.The divergence angle of ultrasound and the angular energy distribution areresearched firstly during the Q-switched process. For a certain angular distribution oflight intensity of each transverse mode and based on the momentum matchingcondition, the direction of the ultrasonic wave vector corresponding to the direction ofa wave vector occurred Bragg diffraction is calculated. Calculate method of theacousto-optic diffraction efficiency of each transverse mode in the presence of thedivergence angle of ultrasound is confirmed, and then the influences of the length ofthe transducer, ultrasonic power and frequency on the three transverse modes areresearched. Then by analysis of the energy storage and energy release processes duringthe Q-switched process, algorithm model during the Q-switched process is builded. Inthe case of bumping beam is the ideal Gaussian beam, the influences of differentchange rates of acousto-optic diffraction efficiency and different acousto-opticdiffraction efficiencies of different transverse modes while changing ultrasonic wavepower on the pulse output settling time, peak power, pulse width, energy, energy ratioof fundamental mode share during the energy release process are researched. Finally,based on this study, how to improve the energy share of fundamental mode in outputlight is studied.