Abstract

As its name implies, coherent upconversion would allow nuclear materials to be pumped with an intense but conventional coherent source such as a laser. Threshold powers would be much lower than usually projected for a gamma-ray laser and the pump sources could be drawn from a more mature technology. This scheme for pumping a gamma-ray laser depends on the development of states of nuclear excitation dressed by the photons of the pump field. Of particular importance is that the metastability of adressed isomeric state would be released, and with it the stored energy. Recently we published a Letter showing a rather close agreement between our first experimental measurements and a dressed state theory. As described in this paper, additional spectroscopic detail has been measured which now shows strong quantum structure that resulted from the formation of a resonance arising from certain dressed states of Fe-57 driven by intense rf fields. Moreover, these dressed states of nuclear excitation were found to have just the properties expected. Critical significance accrues from this result because the dressed states were created in iron nuclei diluted in nonmagnetic stainless steel by the transfer of a driving B-field that had been greatly enhanced by the ferromagnetism of an adjacent layer. In this way the dependence of dressed nuclear states on the ferromagnetism of their diluent was eliminated.

© 1986 Optical Society of America