Tunable resonance fluorescence monochromator with sub-Doppler spectral resolution

A cesium-based resonance fluorescence monochromator with a spectral resolution of 200 MHz and a tunable response over the D-2 absorption line of cesium (380 MHz) is described. The narrow spectral response is achieved through excitation of a monokinetic population of the 6 (2)P(3/2)degrees state by arrangement of the excitation lasers in either a copropagating or a counterpropagating orientation. The narrow spectral response of the detector allows for excitation of specific hyperfine components involved in the 6 P-2(3/2) (F = 3 - 5) to 6 D-2(5/2) (F = 2-6) transition (917.23 nm). The selectivity gained through resolving specific hyperfine transitions allows for a photon detector that is both spectrally tunable and narrow. We report the sub-Doppler linewidths achieved through various laser beam orientations. We also describe how these beam geometries can be applied to spectrally narrow and tunable image detection. (C) 2001 Optical Society of America.