Some Recent Developments in CW Optically Pumped FIR Lasers

As pointed out in 1978 by Hodges at the Third International Conference on Infrared and Millimeter Waves [1], a review of advances in optically pumped FIR lasers (OPFIRL's) since the pioneering work of Chang and Bridges[2] represents a formidable challenge; how much more so today when six full sessions were devoted to the subject at the Fifth International Conference in Wrzburg [3]. Since good review articles already exist [1,4,5,6], it is not the purpose of the present paper to be encyclopaedic, but rather to outline some developments in the last two years. Detailed references will be given in the text; a comprehensive source is in work already cited [3,6] or in the Journal of IR and Mm Waves [7]. Again for reasons of space, it is necessary to adhere strictly to advances in cw OPFIRL's.