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

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 1 030 nm. Firstly,the second harmonic radiation is achieved with 60% optical-to-optical (1 030 to 515 nm)conversion efficiency. Then,the third harmonic generation based on type. and type. phase-matching BBO crystals are studied respectively. With the type. phase-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 similar to 14%. The ultraviolet output power of 1.01 W is obtained corresponding to an optical-to-optical(1 030 to 343 nm) conversion efficiency of 20.2% with type. phase-matching BBO. The beam quality of the high power ultraviolet laser at 343 nm is better than 1.3.