Abstract

At first approach it would seem that the prospects for all ultrashort wavelength lasers would be vitiated by the basic v³ dependence of electron transition probabilities that drastically limits the storage of pump energies. However, there are some unique advantages of a gammaray laser that would accrue from its operation upon electromagnetic transitions of nucleons as opposed to electrons. First, the constant linking v³ with lifetime is more favorable by orders-of-magnitude because of the accessiblity of a variety of transition moments. The effects pumped by an input pulse can be integrated up to larger values for longer times. Secondly, nuclear metastables store keV and even MeV for years. With upconversion schemes most of the pump power is input long before the time of use and triggering requirements are small. Nuclear transitions need not have thermal broadening and natural linewidths are routinely obtained. Without broadening, electromagnetic cross sections are large and values for 1 Å transitions typically exceed the cross section for the stimulation of Nd in YAG. Finally, working metastables can be concentrated to solid densities. As candidates for ultrashort wavelength media, nuclear populations clearly offer some strong advantages.

© 1992 IQEC