Second-harmonic light scattering near two-photon resonance

Iu. M. Kirin, Sergey G. Rautian, Vladimir P. Safonov +1 more

M. G. Payne, W. R. Garrett, J. P. Judish +1 more

We describe here an effect which occurs when a first laser is tuned near a dipole allowed three‐photon resonance and a second laser is used to complete a dipole allowed four‐photon resonance between the ground state ‖ 0≳ and an excited state ‖ 2≳. In this process three photons are absorbed from the first laser and one photon from the second; so that if the ‖ 0≳ to ‖ 2≳ transition is two‐photon allowed the transition is also pumped resonantly by the third harmonic field due to the first laser and the second laser field. When the second laser is strong enough to cause strong absorption of the third harmonic light, and the phase mismatch, Δk is large and dominated by the nearby resonance, a destructive interference occurs between the pumping of the ‖ 0≳ to ‖ 2≳ transition by two‐ and four‐photon processes.

S Kunze, Stephan Dürr, Gerhard Rempe

Slow atoms from a magneto-optical trap are used to study diffraction from a near-resonant standing-wave light field. Long interaction times make it possible to observe unidirectional Bragg scattering. In particular, the Pendellösung interference effect between two resonant momentum states is demonstrated for first- and second-order diffraction. The oscillation frequency of second-order scattering shows a transition from a four-photon–type process at low light intensity to a two-photon–type process at higher intensity. The data are in quantitative agreement with a theoretical description which takes into account lowest-energy momentum states.

Augusto da Silveira. Rodrigues

M. D. Reid, H. J. Carmichael, Daniel F. Walls

Gerhard Rempe, S. Kunze, Stephan Dürr

Slow atoms from a magneto-optical trap are used to study difiraction from a near-resonant standing-wave light fleld. Long interaction times make it possible to observe unidirectional Bragg scattering. In particular, the Pendellosung interference efiect between two resonant momentum states is demonstrated for flrst- and second-order difiraction. The oscillation frequency of second-order scattering shows a transition from a four-photon{type process at low light intensity to a two-photon{type process at higher intensity. The data are in quantitative agreement with a theoretical description which takes into account lowest-energy momentum states.