We report the first self-Q-switched Yb-doped GdYSiO5（Yb：GYSO） laser operating at 1080 nm.Stable Q-switched pulses with a repetition rate of 18.1 k Hz and pulse duration of 9.45 μs are obtained.A maximum average output power of452.6 m W is achieved with a 1% transmission output coupler.With a 3% transmission output coupler,the shortest pulse width of 6.6 μs is obtained.It demonstrates that Yb：GYSO crystal can be simultaneously employed as a saturable absorber and a gain medium to generate microsecond Q-switched pulses in the near infrared region.
Shuang GongJin-Rong TianHe-Yang Guo YuZi-Kai DongChang-Xing XuWen-Ping ZhangYan-Rong Song
A ring-cavity synchronously-pumped optical parametric oscillator （OPO） is investigated based on periodically poled KTi：OPO4 （PPKTP）. The wavelength of the signal wave covers from 1 000 to 1500 nm, the output power is 32.3 mW, and idler wave spectrum range from 1 800 to 2 500 nm is detected. By inserting a BBO or BIBO crystal respectively, a stable and adjustable range from 450 to 650 nm light is obtained. Three to six wavelengths can be output simultaneously.
Self-Q-switching is observed in a bulk Yb：KGd（WO4）2 oscillator without any additional modulating elements. The output power reaches 434.4 mW at a pump power of 13.67 W, corresponding to pulse repetition rate of 125 kHz and a pulse duration of 2.5μs, respectively, The mechanism of self-pulse formation is explained by the re-absorption effect of the Yb^3＋ ion in Yb：KGd（WO4）2.
