全固态飞秒激光高光束质量三倍频研究(特邀)

High Beam Quality Third Harmonic Generation with All-solid-state Femtosecond Laser(Invited)

对全固态飞秒激光三倍频产生高光束质量343 nm飞秒激光进行了系统研究。基频光源为脉冲宽度为105 fs、重复频率为76 MHz、中心波长为1030 nm的商用Yb:KGW锁模激光器,利用1.7 mm长LBO晶体获得60%的二倍频转换效率,然后分别研究了基于BBO晶体Ⅱ类相位匹配和Ⅰ类相位匹配的三倍频产生。在基频光功率为5 W的条件下,利用Ⅱ类相位匹配的BBO晶体,获得的最大平均功率为0.71 W,三倍频转换效率约为14%;利用Ⅰ类相位匹配的BBO晶体,获得平均功率为1.01 W的紫外激光输出,三倍频转换效率为20.2%。获得的343 nm紫外激光的光束质量优于1.3。

The generation of 343 nm femtosecond laser with high beam quality by the third harmonic generation of an all solid state femtosecond laser was reported.The fundamental harmonic is a commercial Yb:KGW mode-locked laser with a pulse duration of 105 fs,a repetition rate of 76 MHz and a central wavelength of 1030 nm.Firstly,the second harmonic radiation is achieved with 60%optical-to-optical(1030 to 515 nm)conversion efficiency.Then,the third harmonic generation based on typeⅡand typeⅠphase-matching BBO crystals are studied respectively.With the typeⅡphase-matching BBO,the maximum output power of 0.71 W is achieved under the fundamental power of 5 W,which corresponding to the optical-to-optical conversion efficiency of~14%.The ultraviolet output power of 1.01 W is obtained corresponding to an optical-to-optical(1030 to 343 nm)conversion efficiency of 20.2%with typeⅠphase-matching BBO.The beam quality of the high power ultraviolet laser at 343 nm is better than 1.3.