Effect of externally injected radiation on amplified spontaneous emission in CO

The effect of externally injected radiation on the two-photon laser-induced amplified spontaneous emission (TP-LIASE) is reported. The wave generated via the same LIASE process in a seeder cell acts as a seeder field for the inverted medium created in a main cell. A nearly tenfold gain is achieved i n the B(1)Sigma (4) --> A (1)Pi (0, 3) transition of the CO molecule. We de monstrate that the single rotational transition in the B (1)Sigma (4) --> A (1)Pi (0, 4) band is selectively amplified by injection of laser radiation . This pump and seed arrangement facilitates detection of molecular spectra by simply tuning the seed-laser frequency. The polarization effect of the input laser radiation is briefly discussed.