Fresnel zone plates for reconfigurable atomic waveguides.

Fresnel zone plates (FZPs), with patterns of 1μm resolution and 108+ 'pixels', allow the formation of clean, diffraction-limited foci - but have a static phase profile. Spatial light modulators (SLMs) allow dynamic control of spatial beam intensity and phase - but are bulky and currently limited to roughly 10μm pixel sizes and 1 Mega-pixel formats. Here, we present a 'best-of-both' kind of FZP, scalable to rings orders of magnitude larger than those possible via direct SLM generation. It is equivalent to a plano-convex donut lens, whereby light's local intensity and global phase at the FZP map directly onto the focal plane. The same FZP under different SLM illumination can generate: rings and arcs, double-rings, phase windings, and ring lattices (or dynamic combinations thereof). The smooth and adaptable near-field waveguide that this enables will be ideal for Sagnac interferometry with ultracold atoms.