Passively cascade-pulsed erbium ZBLAN all-fiber laser.

We propose and numerically demonstrate a cascade pulsing mechanism in a CW-pumped Er³⁺:ZBLAN all-fiber laser system. In the design, the laser was pumped at 980 nm and passively Q-switched at 1.6 μm. The Q-switched resonance reduced the population on ⁴/13/2 of the erbium gain fiber, thereby creating a population inversion between the levels of 4/11/2 and ⁴/13/2, and instantly inducing an intense gain-switched pulse at 2.7 μm. Sequential 2.7-μm single-mode pulsing with a pulse energy of 170 μJ and a peak power of 6 kW was achieved with an absorbed pump power of 0.65 W.