Efficient, optically pumped NH3 oscillators and amplifiers operating in the mid-infrared.

Detailed measurements of the performance of NH3 amplifiers in both small-signal and saturated gain conditions are reported. The results of these investigations are used to design efficient line-tunable NH3 oscillators. The initial measurements were made with the apparatus in an oscillator/amplifier configuration. A rate equation model with no adjustable parameters is used. The model has been validated by comparison to experiment over a wide range of amplifier pressures (170-700 Torr), temperatures (200-300 K), mixtures (0.05-0.2% NH3), and buffer gases (Ar, N2, and He). Gain measurements were made for several different NH3 transitions, and agreement with the model was better than ±15% for all conditions. The experiments demonstrate that optically pumped NH3 provides an efficient high-gain amplifier in the mid-IR region.