Resonantly enhanced Bragg-scattering spectroscopy of an atomic transition

• We observed the backward resonance Bragg scattering spectra from a PDG in the thermal vapor.
• The achieved Bragg scattering spectroscopy has sub-natural linewidths and high S/N.
• The intensity and linewidth of the Bragg scattering signal depend on the powers of the pump and probe beams. So, according to different requirements, we can adjust these powers respectively to obtain the optimal Bragg scattering spectrum in actual experiments.
• The central position and the line shape of the achieved Bragg scattering spectra do not depend on the powers of the optical fields. This conclusion is specially useful if we would like to develop a RBS spectroscopy based on the atomic PDG.

A novel resonantly enhanced Bragg-scattering (REBS) spectroscopy from a population difference grating (PDG) is reported. The PDG is formed by a standing-wave (SW) pump field, which periodically modulates the space population distributions of two levels in the 87Rb D1 line. Then, a probe beam, having identical frequency and orthogonal polarization with the SW pump field, is Bragg-scattered by the PDG. The research achievement shows that the Bragg-scattered light is strongest at an atomic transition, and forms an REBS spectrum with a high signal-to-noise ratio and sub-natural linewidth. The observed REBS can be applied in precise frequency measurements.