9 research outputs found
Generation of continuous-wave THz radiation by use of quantum interference
We propose a scheme for generation of continuous-wave THz radiation. The
scheme requires a medium where three discrete states in a
configuration can be selected, with the THz-frequency transition between the
two lower metastable states. We consider the propagation of three-frequency
continuous-wave electromagnetic (e.m.) radiation through a medium.
Under resonant excitation, the medium absorption can be strongly reduced due to
quantum interference of transitions, while the nonlinear susceptibility is
enhanced. This leads to very efficient energy transfer between the e.m. waves
providing a possibility for THz generation. We demonstrate that the photon
conversion efficiency is approaching unity in this technique.Comment: 18 pages, 4 figure
Efficient microwave-induced optical frequency conversion
Frequency conversion process is studied in a medium of atoms with a
configuration of levels, where transition between two lower states is driven by
a microwave field. In this system, conversion efficiency can be very high by
virtue of the effect of electromagnetically induced transparency (EIT).
Depending on intensity of the microwave field, two regimes of EIT are realized:
''dark-state'' EIT for the weak field, and Autler-Townes-type EIT for the
strong one. We study both cases via analytical and numerical solution and find
optimum conditions for the conversion.Comment: 15 pages, 5 figure
Sub-Doppler cooling of three-level A Atoms in space-shifted standing light waves
We present an investigation of an alternative mechanism for sub-Doppler cooling of atoms, based on coherent population transfer in three-level LAMBDA systems. The mechanism considered is that of a LAMBDA atom interacting with two standing light waves with a mutual spatial phase shift phi not-equal 0. The spatial dependence of the level populations of the LAMBDA atom for different values of phi is presented. For phi not-equal 0, this clearly demonstrates coherent population transfer in an atom with transverse motion along the space-shifted nodes and antinodes of the two standing waves. We show that this allows translational temperatures well below the Doppler limit T(D) = hgammaBAR/k(B) to be achieved