New phenomena related to pulsed far-infrared superradiant and Raman emissions

Resonant four wave mixing in NH3 and CH3F

Optically pumped molecular gas lasers have proved to be a convenient and versatile source of coherent mid-infrared (MIR) radiation. The present state of development and understanding of these lasers is reviewed in this article. Emphasis has been placed on recent results with a view to complement the earlier reviews of the field.

Mid-infrared optically pumped molecular lasers

The six-level model using a density matrix approach to simulate properties of a gas resorant media in optically pumped FIR lasers was developed. The model accounts for multiphoton as well as parametric processes. Advantages of the developed model are demonstrated by calculation and discussion of the gain and saturated emission spectra of CH3F laser when transitions with different J rotational numbers of CH3F are pumped.

Emission spectra of the tunable Raman CH3F optically pumped fir laser

A fully resonant four level system is analyzed using the density matrix method for description and comparison of simultaneously existing multiphoton Raman and parametric processes in optically pumped FIR lasers. The possibility of utilising dc Stark-induced three-wave mixing processes is discussed for the production of far infrared radiation in case of two pump waves. Coupled three photon interactions and coupled Raman processes are discussed too. Calculated spectra of gain for three photon interactions and Raman processes at different values of quantum number M and field intensities and the dependence the field intensities on the distance counted from FIR tube input are shown.

S.J. Petuchowski

Papers

Evidence of four-wave parametric interaction in optically pumped NH3