Generation of continuously tunable 5 µm coherent radiation by second harmonic conversion of the emission of a multi-atmosphere TE CO2 laser in AgGaSe2

Abstract

Operation of a continuously tunable coherent source in the 5 micron region of the mid-infrared by frequency doubling of the continuously tunable emission of a multi-atmosphere TE CO2 laser in an AgGaSe2 crystal is reported. The performance has been characterized with regard to energy and power conversion efficiency as well as the threshold pump intensities at which the onset and termination of the second harmonic (S H) conversion process occurs. The absence of a gain switched peak in the emission of the pump laser that stemmed from its operation with a lean CO2 gas mixture enabled error-free threshold measurement for the onset of the S H generation process. Further, the excellent phase and amplitude synchronization of the SH emission with the pump pulse, that could be established by taking advantage of the rich modulation in the emission of the multimode pump laser in nanosecond time scale, bore experimental testimony to the instantaneous nature of the SH generation process.