Spontaneous mode splitting and frequency shifting due to coherent effects in optically pumped molecular lasers

A new kind of spontaneous mode-splitting is predicted for resonant (near resonant) pumped molecular lasers, resulting from pump field induced Rabi splitting of the emission line-shape. General conditions are presented for the occurrence of mode-splitting in homogeneously broadened systems. Results of detailed analysis pertaining to specific mid- and far-infrared lasing transitions in NH/sub 3/ show that much effects should be observable under typical experimental conditions as oscillatory instabilities in the emission. For the case of off-resonant (Raman) emission, pump-intensity dependent unidirectional cavity mode frequency shifting is predicted. This is confirmed for a CO/sub 2/ laser pumped 12.08 μm laser