Sub-15-ns Passively Q-Switched Er:YSGG Laser at $2.8~\mu$ m With Fe:ZnSe Saturable Absorber

At present, pulse widths of passively Q-switched mid-infrared lasers at
${\sim }2.8 {\mu }\text{m}$
have been limited to be at least several hundreds of nanoseconds. In this letter, by configuring a compact laser resonator, we report on diode-pumped continuous-wave and passively Q-switched mid-infrared Er:YSGG lasers. Laser emission at 2797 nm is achieved with a maximum output power of 0.63 W and slope efficiency of 13.9% in continuous-wave mode. Using polycrystalline Fe:ZnSe as saturable absorber, the passively Q-switched operation is also realized with the narrowest pulse width of about 14.6 ns, which is believed to be the shortest pulse for passively Q-switched mid-infrared lasers. The generated maximum pulse energy and peak power are 5.05
${\mu }\text{J}$
and 345.8 W, respectively.