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AssigneeBell Telephone Laboratories, Incorporated
InventorsJohn Ernst Bjorkholm, Paul Foo-Hung Liao
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Improved atomic beam deflection and improved isotope separation, even in vapors, is proposed by substituting the A.C. Stark effect for the baseband chirp of the pushing beam in the prior proposal by I. Nebenzahl et al, Applied Physics Letters, Vol. 25, page 327 (September 1974). The efficiency inherent in re-using the photons as in the Nebenzahl et al proposal is retained; but the external frequency chirpers are avoided. The entire process is performed by two pulses of monochromatic coherent light, thereby avoiding the complication of amplifying frequency-modulated light pulses. The A.C. Stark effect is provided by the second beam of coherent monochromatic light, which is sufficiently intense to chirp the energy levels of the atoms or isotopes of the atomic beam or vapor. Although, in general, the A.C. Stark effect will alter the isotope shift somewhat, it is not eliminated. In fact, the appropriate choice of frequencies of the pushing and chirping beams may even relax the requirements with respect to the isotope absorption line shift for effective separation. That is, it may make the isotope absorption lines more easily resolvable.
A method for separation of isotopes comprising the steps of supplying a mixture of the desired isotope and at least one isotope not desired to an interaction region, supplying a first coherent optical beam that is pulsed and selected for resonance radiation interaction, whereby a force is to be exerted on the selected isotope, the frequency of said first source being offset from the resonance by a selected amount, supplying to said mixture a second coherent optical beam that is pulsed with sufficient intensity to Stark-shift the resonance transition through coincidence with the photon energy of the first source, said second optical beam having a chirp rate of optical intensity that is appropriate for adiabatic rapid passage, and providing two sequential oppositely-directed passes of the first beam through the mixture coincident with appropriate Stark shifts produced by the second beam, yielding absorption by the selected isotope on the first pass and stimulated re-emission by the selected isotope on the second pass.
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