Innovative high-gain optically pumped far-infrared laser.

A new optically pumped far-infrared (FIR) laser with separate pump beam reflector and FIR output coupler has been developed. The new design greatly simplifies the tuning of the laser and enables the optimization of the pump beam absorption without affecting the laser alignment. Working with formic acid (HCOOH) vapor pumped by a 30 W CO2 laser at the 9R20 line, a high laser gain of 3 dB/m and power conversion efficiency of 16.4% of the Manley-Rowe limit are achieved for the FIR wavelength of 433 µm.