Compositionally tuned lasers: Practical lasers at designer wavelengths

A general need exists for practical solid state lasers at particular wavelengths. For NASA, these particular wavelengths are needed for remote sensing of atmospheric constituents such as water vapor and green house gasses. Transition metal solid state lasers can be widely tuned, however, they usually possess a relatively short upper laser level lifetime or a relatively small emission cross section. Either of these parameters can limit the practicality of transition metal lasers. On the other hand, lanthanide series solid state lasers have attractive upper laser level lifetimes and emission cross sections, however they have narrow tuning ranges. This problem is solved by utilizing the concept of compositional tuning of lanthanide series lasers. Compositional tuning effects, including the tuning range, are predicted using quantum mechanical calculations. They are also experimentally verified by means of spectroscopic measurements. Practical examples for two lanthanide series lasers that were compositionally tuned to a preselected water vapor absorption feature are presented. Both flash lamp pumped and diode pumped laser results are presented.