LD-Pumped Watt-Level SESAM Passively Q-Switched Alexandrite Laser

Alexandrite lasers are attractive choices for 700-800 nm band, and they are necessary in many applications. A red laser diode (LD) pumped watt-level passively Q-switched Alexandrite laser with a semiconductor saturable absorber mirror (SESAM) is presented. A continuous wave (CW) laser with an average power of 2.5 W was obtained. Customized SESAMs were employed to enable a 749.6-nm pulsed Alexandrite laser with an average power of 0.904 W, a repetition rate of 20.27 kHz, and a pulse energy of $44.59\mu \text{J}$ , when the pump power was 26.5 W. To the best of our knowledge, this is the highest average power from SESAM passively Q-switched Alexandrite laser, which is one order of magnitude higher than previous reported results.