Diode-Pumped Passively Mode-Locked Tm:  $\hbox{CaGdAlO}_{4}$ Laser at 2-  $\mu \hbox{m}$ Wavelength
We report on a diode-pumped passively mode-locked picosecond Tm:CaGdAlO4 (Tm:CALGO) laser using a semiconductor saturable absorber mirror as the mode locker. With Tm:CALGO disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration of 27 ps, repetition rate of 128.6 MHz, and maximum average power of 330 mW at 1949.5 nm. To the best of our knowledge, this is the first demonstration of a mode-locked Tm:CALGO disordered crystal laser. The continuous-wave (CW) laser performance of Tm:CALGO was also investigated, and the maximum CW power was 730 mW. Our research results show that Tm:CALGO crystal is an excellent bulk medium for picosecond pulse generation at 2-μm wavelength.