  We present a novel achromatic, planar, periodic mirror structure for
single-beam magneto-optical trapping and demonstrate its use in first- and
second-stage cooling and trapping for different isotopes of strontium. We refer
to it as Fresnel MOT as the structure is inspired by Fresnel lenses. By design,
it avoids many of the problems that arise for multi-color cooling using planar
structures based on diffraction gratings, which have been the dominant planar
structures to be used for single-beam trapping thus far. In addition to a
complex design process and cost-intensive fabrication, diffraction gratings
suffer from their inherent chromaticity, which causes different axial
displacements of trap volumes for the different wavelengths and necessitates
tradeoffs in their diffraction properties and achievable trap depths. In
contrast, the Fresnel reflector structure presented here is a versatile,
easy-to-manufacture device that combines achromatic beam steering with the
advantages of a planar architecture. It enables miniaturizing trapping systems
for alkaline-earth-like atoms with multiple cooling transitions as well as
multi-species trapping in the ideal tetrahedral configuration and within the
same volume above the structure. Our design presents a novel approach for the
miniaturization of cold-atom systems based on single-beam MOTs and enables the
widespread adoption of these systems.
