Abstract

We passed a transversely cooled sodium atomic beam through an optical standing wave, which channeled the atoms into the intensity minima (maxima) for light tuned below (above) the sodium 3²S_1/2 → 3²P_3/2 resonance frequency. The channeled atoms retained their spatial distribution when they were deposited onto the silicon surface. The surface was thus covered by a permanent periodic sodium grating with an area of 1 x 0.1 cm² and a period of d = 294.3 ±0.3 nm, which is half the wavelength of the standing wave field. The entire grating was completed in 10 min. We measured the period of the grating by backscattering weak probe light. The probe light had a wavelength λ, which we varied between 5580 and 5800 Å, and was incident at an angle ϕ relative to the normal. There is constructive interference when the angle θ with respect to the normal to the grating is such that λ = d(sin θ + sin ϕ). The dependence of θ on ϕ allowed us to measure d. Semiclassical theory suggests the width of the lines in the grating could be of the order of 100 Å.

© 1992 Optical Society of America