Forward light scattering from a dense and cold microscopic 87Rb sample

In this paper we report on the near-resonance forward scattering of light in a cold atomic sample of $^{87}$Rb ranging in density from $10^{11}$ to $10^{14}$ atoms/cm$^3$. The sample, initially prepared in a magneto-optical trap, is loaded into a far-off-resonance trap (FORT) with a temperature of $\sim$100 $\mu$K and Gaussian radii of $\sim$3 $\mu$m and $\sim$280 $\mu$m in the transverse and longitudinal directions, respectively. Here the $F=2\to F'=3$ nearly closed hyperfine transition is studied; in this case, far-off-resonance inelastic Raman transitions are weak. The experimental geometry consists of tightly focusing the near-resonance beam through the optically deep region of the FORT and collecting the transmitted light as a function of detuning from resonance. A shift in the spectral distribution of transmitted light is observed as a function of sample density.