NEAR-FIELD DIFFRACTION GRATING FOR ATOMS

We propose to use the periodic light potential of an evanescent light wave produced on the surface of a dielectric prism and modulated throu gh the absorption in parallel metal strips applied onto the dielectric surface as a diffraction grating and a coherent beam splitter Tor a p recooled atomic beam. We have measured the spatial intensity distribut ion of the near field over the surface of such a microstructure using a photon scanning tunnelling microscope. The microstructure with a per iod of 10 mu m was formed by nickel grooves 40 nm thick and 3 mu m wid e fabricated on the quartz surface. The possibility of coherent splitt ing of a precooled atomic beam into components of approximately the sa me intensity with an angular splitting of a few milliradians is shown using the semiclassical approach. (C) 1998 Elsevier Science B.V.