APPLICATION OF ENERGY UP-CONVERSION SPECTROSCOPY TO NOVEL LASER AND PHOSPHOR DESIGN

Energy-transfer and sequential-absorption upconversion processes, normally considered detrimental to conventional laser operation, are rapidly emerging as the key to an exciting new class of optical device. Energy-upconversion processes may be designed to take advantage of strong rare earth ion emission transitions in the visible region and of valuable co-incidences with diode-laser outputs in the near-infrared to produce compact visible lasers. This paper reviews the use of sequential-absorption and energy-transfer spectroscopy to derive information that is essential to the optimization of novel device designs as well as 'conventional' laser or phosphor designs. Transfer-rate extraction using upconverted temporal transients, determination of high-lying energy levels using sequential-absorption laser spectroscopy, ion dimer identification by line-narrowing experiments and direct identification of energy storage states using dual-laser techniques are presented. The use of dimer-dominated host crystals, such as CsCdBr3, that can be used to isolate individual energy-transfer rates relevant to the optimization of many different laser types, is emphasized.