Optical pumping of Rb vapor using high-power Ga1-xAlxAs diode laser arrays.

Abstract

The use of high-power ${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Al}}_{\mathit{x}}$As diode laser arrays for optical pumping of Rb vapor has been examined both theoretically and experimentally. Our studies show that large atomic polarizations can be obtained using the broad spectral output of a diode laser array if the Rb resonance line is collisionally broadened by several atmospheres of a buffer gas. The objective was to study the effectiveness of diode laser arrays as light sources for optically pumped spin-exchange polarized $^{3}\mathrm{He}$ targets. The average Rb polarization was deduced at three different Rb vapor pressures using the polarization induced in the $^{3}\mathrm{He}$ buffer gas. The largest $^{3}\mathrm{He}$ polarization observed was 53% using a 20-W diode array with 1.9-nm full width at half maximum spectral width in 10.5 amagat of $^{3}\mathrm{He}$. This result compares favorably with other light sources for this target. The measured average Rb polarizations are compared to theoretical calculations.