Density effects in forward scattering of resonant light in rubidium vapor

Transmission of light through an atomic sample placed between crossed polarizers in a magnetic field is jointly determined by Faraday rotation and net absorption: transmission increases with rotation and decreases with absorption. Both rotation and absorption are proportional to the atomic density N0, hence, in a certain range of N0, the two effects may compete yielding a distinct density dependence of the transmitted light. We have studied such dependence in rubidium vapor for N0 = 7.5*10^9 to 7.5*10^11 at/cm^3 with resonant laser light. We present interpretation of the competition effect and discuss its possible application for atomic density determination.