Degenerate four-wave mixing (DFWM) line shapes are investigated in sodium vapor near the D2 resonance line using nearly Fourier-transform-limited pulses. At low pump intensities sub-Doppler resolution is obtained. When the Rabi frequency associated with the pump intensity becomes comparable with the ground-state hyperfine frequency separation of sodium, each component of the double-peaked DFWM spectrum splits further into two components. An adiabatic-following model explains the near-resonant intensity dependence of the DFWM signal. A qualitative explanation of the observed splitting is also given.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics