| Among many laser devices,high-power picosecond green solid-state lasers are widely used in high-precision machining,laser medical treatment,and laser ranging because of their narrow output pulse width,high peak power,and compact structure.However,due to the self-focusing effect of the high-power picosecond laser during power amplification,optical components may be easily damaged,resulting in ultrashort pulsed solid-state lasers having difficulty obtaining high power output and poor output beam quality.In order to obtain a high-power picosecond green light output,it is of great significance to seek ways to increase the frequency conversion efficiency and improve the quality of a 100-watt-level fundamental optical beam.This article has carried on the relevant experimental research to these questions,finally realized the maximum 123 watts of the 1064 nm picosecond baseband light output under k Hz repetitive frequency;and proposed the frequency double beam combining method,increased the frequency doubling efficiency from 48% to 71% A 532 nm picosecond green light output with a power of 33 W and a pulse energy of 33 m J was obtained.The content of the paper is mainly divided into the following sections.1.Introduce the research status and application value of pulsed picosecond picosecond laser amplification at home and abroad,including the generation mechanism and application fields,and introduce the main research content of this article.2.The nonlinear optical frequency conversion theory and the generation method of high-power pulsed picosecond lasers are introduced.The steady-state and transient three-wave coupling equations are deduced,and the critical phase matching angles of LBO(lithium triborate)crystals are calculated.The frequency of the best crystal length.At the same time,the theory of generation,regenerative amplification and traveling wave amplification of picosecond pulse train is analyzed and elaborated,which provides a theoretical basis for the subsequent experimental part.3.The related theory about the thermal effect of laser crystal is described.Thetemperature and thermal stress of Nd:YAG crystal under lateral pumping conditions are numerically simulated.A side-pumped Nd:YAG rod dual-module single-pass amplifier was designed to effectively reduce the damage of the optical components in the amplifier stage by using a beam shaping mirror.Under a 1 k Hz repetitive frequency,the 8 W pulse train laser passes through a two-stage dual-module single After amplification,a 1064 nm laser output with an average power of 123.6 W was obtained.4.The related theories of thermal effects of nonlinear crystals are introduced.A highefficiency,high-power doubled-frequency experiment was conducted.Using two LBO crystals,a 7W pulse train laser was passed through two frequency-doubling crystals and frequency-multiplied by a polarization angle beam,resulting in a total of 5W green light.Output,the total frequency conversion efficiency reached 71.4%,and by changing the optical path difference between the two frequency-doubling crystals,the pulsefrequency doubled light output of different combinations of waveforms was obtained.Using class I angle phase matching,After the 1064 nm laser frequency generated by the first-stage amplification,a 14.6W green light output is obtained,the frequency doubler conversion efficiency is 45.6%,and the second-stage amplification laser frequency multiplication generates a 33 W green light output,and the frequency doubler conversion efficiency is 38.4%. |
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