Optimal binary gratings for multi-wavelength magneto-optical traps

TL;DR

This paper develops an empirical model to optimize binary gratings for multi-wavelength magneto-optical traps, enhancing laser cooling efficiency across different atomic species for quantum technology applications.

Contribution

It introduces a simple empirical fit for diffraction efficiency of binary gratings at various wavelengths, simplifying design for multi-wavelength quantum devices.

Findings

Empirical model accurately predicts diffraction efficiency within a few percent.

Optimized gratings enable improved multi-wavelength laser cooling.

Model simplifies complex 3D calculations for practical design.

Abstract

Grating magneto-optical traps are an enabling quantum technology for portable metrological devices with ultracold atoms. However, beam diffraction efficiency and angle are affected by wavelength, creating a single-optic design challenge for laser cooling in two stages at two distinct wavelengths - as commonly used for loading e.g. Sr or Yb atoms into optical lattice or tweezer clocks. Here, we optically characterize a wide variety of binary gratings at different wavelengths to find a simple empirical fit to experimental grating diffraction efficiency data in terms of dimensionless etch depth and period for various duty cycles. The model avoids complex 3D light-grating surface calculations, yet still yields results accurate to a few percent across a broad range of parameters. Gratings optimized for two (or more) wavelengths can now be designed in an informed manner suitable for a wide class of atomic species enabling advanced quantum technologies.