Optical frequency conversion processes in atomic Rydberg states

Abstract
We present an analysis of optically pumping Rydberg states in alkalis to generate coherent lasers in the infrared and far‐infrared spectral regions. Based on the previous accurate experimental and theoretical data on these states, our conclusion is that such laser systems can be operated either pulsed or cw and possess narrow linewidths, high gains, and considerable tunability. Wavelengths near 16, 12, 8.6, and 7.7 μm which are of interest for isotope separation are achievable with milliwatt power levels. Specific examples for Na vapor are given.