32-fs Kerr-lens mode-locked alexandrite laser pumped by a Pr:LiYF4 laser at 639 nm

We report on an alexandrite laser pumped by an all-solid-state Pr:LiYF₄ (YLF) continuous-wave laser for the first time, to the best of our knowledge. The self-developed Pr:YLF laser at 639 nm has a power of 3.8 W. For continuous-wave alexandrite laser operation, we have achieved continuous tuning of the wavelength range from 718 nm to 785 nm. For Kerr-lens mode-locked alexandrite laser operation, we have realized a pulse width of 32 fs, which, to our knowledge, is currently the shortest pulse width for alexandrite laser. In the current research on alexandrite femtosecond lasers, 532 nm and 589 nm pump sources based on solid-state laser nonlinear frequency conversion technology are commonly used. The 639-nm laser we use in this work is the fundamental wave, which exhibits advantages in efficiency and system compactness.