Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 48: Photonik I

Q 48.1: Talk

Wednesday, March 21, 2007, 16:30–16:45, 5J

Optical self-imaging of gratings fabricated using colloidal crystals and soft-lithography — •Manuel Gonçalves, Ralf Ameling, André Siegel, and Othmar Marti — University of Ulm - Inst. Experimental Physics, Albert-Einstein-Allee 11, D-89069 Ulm, Germany

Since the observation of the Talbot effect in cold atoms by Chapman et al. [1], the self-imaging of classical and matter waves regained attention, both in applications and in the investigation of the interaction of periodic light fields with atom molasses. However, the interpretation of the Talbot effect relies on the Fresnel diffraction approximation. This is adequate for arrays of diffraction where the period is large the wavelength. When the size of the diffraction object of the order of the wavelength the approximation fails.

We show that two-dimensional arrays of microscopic polystyrene spheres and other structures, fabricated using these crystals, behave as arrays of sharp light sources and present self-imaging at distances different of those predicted by the classical Talbot effect.

Theoretical models based on scalar and on the vector diffraction theory, without the Fresnel approximation, were investigated. The Talbot lengths obtained are close to the experimental results, but different from those obtained with the classical formulation.

The periodic structures fabricated using colloidal crystals and soft-lithography techniques may be used to generated complex light fields to manipulate atom molasses.

[1] M. S. Chapman et al., PRA 51(1) R14, 1995.