高峰值功率KDP晶体四倍频266nm紫外激光器

High peak power fourth harmonic 266nm UV laser using a KDP crystal

报道了一种灯泵浦结构的Nd：YAG晶体电光调Q高峰值功率266nm紫外激光器。结合磷酸二氢钾（KDP）晶体性质,基于倍频理论,分析了考虑走离效应情况下存在相位失配量时KDP晶体长度对转换效率的影响。该激光器采用紧凑的平平腔结构,灯泵浦Nd：YAG晶体电光调Q 1064nm激光作为基频光,腔外采用Ⅱ类匹配磷酸钛氧钾（KTP）和Ⅰ类匹配KDP分别作为二倍频和四倍频晶体。利用能量计、示波器等仪器进行测量,激光器重复频率1Hz时,获得脉宽6.0ns,单脉冲能量35mJ的266nm紫外激光输出,峰值功率高达5.83 MW;当重复频率10Hz时,获得单脉冲能量28.9mJ的266nm紫外激光。532~266nm转换效率最高可达31.9%。利用该高峰值功率、窄脉宽266nm紫外激光器,能够实现激光打标、激光雕刻。

A lamp pumped high peak power electro-optical Q-switched Nd：YAG 266 nm UV laser was demonstrated.In combination with the KDP crystal properties,and based on the frequency doubling theory,the influence of KDP crystal length on the conversion efficiency under the condition of existence phase mismatching was analyzed considering the walk-off effect.The compact flat cavity structure was used and the 1064 nm laser generated from lamp pumped electro-optical Q-switched Nd：YAG laser was used as fundamental frequency laser.A type Ⅱ phase-matched KTP crystal and a type Ⅰ phase-matched KDP crystal were used for the extra-cavity second-harmonic generation and fourth-harmonic generation respectively.Using energy meter,oscilloscope and other instruments,the UV laser pulse energy of 35mJ/pulse at the repetition rate of 1Hz and the pulse width of 6.0ns at 266 nm were achieved,the peak power was 5.83 MW.UV laser pulse energy of 28.9mJ/pulse at 266 nm was achieved at the repetition rate of 10 Hz.A conversion efficiency of 532 nm to 266 nm was up to 31.9%.Laser marking and laser engraving can be achieved with this high peak power,short pulse width 266 nm UV laser.