Pulsations in Optically Pumped Formic Acid 433 μm Far Infrared Laser

Pulsation behaviours of optically pumped Formic Acid (HCOOH) 433μm laser are observed. Pulsation frequency varies continuously with tilting the output cavity mirror or changing the HCOOH pressure. Unstable pulsations are observed at a relative high pressure or by changing a cavity mirror with higher output loss.