The conversion efficiency on the sixth harmonic of 1064 nm in KBe2BO3F2 （KBBF） at different gas pressures in two kinds of gases, helium and nitrogen, is measured and compared. In the both gases, maximum conversion efficiency on the sixth harmonic of 1064 nm in high vacuum is nearly 10% of 355 nm, which is almost four times higher than that in low vacuum. The maximum average output power at 177.3 nm is 670 ttW with the repetition rate of 10 Hz and the duration of 20 ps in high vacuum. It indicates that the sixth harmonic generation in high vacuum is more preferable than that in low vacuum.
This paper investigates the scattering effect of domestic 0.5 at% ceramic Nd：YAG. An effective method has been utilized to measure the scattering and absorption coefficients. An end-pumped continuous wave （CW） Nd：YAG ceramic laser was also demonstrated. A maximum output power of 6.7 W at 1064 nm was obtained at an 808-nm pump power of 32.9 W. Conversion efficiency and slope efficiency have been achieved. This indicates that scattering has an important effect on the optical performance of ceramic Nd：YAG.
A high power continuous-wave （CW） diode-pumped Nd：YAG laser operated in heat capacity mode is demonstrated by use of two identical highly efficient diode-pumped laser heads placed in a plane-plane resonator. The laser heads are uniformly pumped with a five-fold symmetrical side-pumping configuration, and each head is able to output maximum output power of 2200 W at 808 nm. Under a total pump power of 4290 W, the output power of the laser at 1064 nm is up to 2277 W, corresponding to an optical-to-optical efficiency of 53.1%.
