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Optimal binary gratings for multi-wavelength magneto-optical traps



Oliver Burrow, Robert Fasano, Michael Wright, Wesley Brand, Wenbo Li, Andrew Ludlow, Erling Riis, Paul Griffin, Aidan Arnold


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.
Optics Express


laser cooling, grating, magneto-optical trap, quantum technology, diffraction, cold atom


Burrow, O. , Fasano, R. , Wright, M. , Brand, W. , Li, W. , Ludlow, A. , Riis, E. , Griffin, P. and Arnold, A. (2023), Optimal binary gratings for multi-wavelength magneto-optical traps, Optics Express, [online],, (Accessed June 17, 2024)


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Created November 20, 2023, Updated June 7, 2024