Abstract

We have studied the temporal decay of a population grating produced on the ground-state hyperfine levels of magneto-optically trapped cesium atoms^1,2. The grating is produced by excitation of the 6S₁ 2(F=4)→ 6P_{3 2}(F’=4) transition by two equal-frequency optical beams that intercept at the cold atom sample forming a small angle (grating writing beams). The excited-state population grating produced by these beams is transferred through optical pumping into the 6S_{1 2}(F=3) population. The transferred grating is probed by a third laser beam resonant with the 6S_{1 2}(F=3)→ 6P_{3 2}(F’=2) transition propagating nearly opposite to one of the grating writing beams. The Bragg diffraction of the probe beam on the ground-state population grating is monitored with a fast photodiode The grating writing beams are chopped (1 µs switching time) and the transient decay of the diffracted beam is monitored. The observed decay is exponential within the experimental resolution

© 1998 IEEE