Inverse Design of Visible Integrated Photonics for an Ultracold Strontium Optical Clock

Abstract

We demonstrate visible integrated photonics, using an inverse-design approach. Tantalum-pentoxide nanophotonics offers <2 dB/cm waveguide loss across 450-2000 nm range. We create a suite of passives, including arbitrary-polarization grating sources for a Sr optical clock.

Antireflective Multi‐Dielectric Metasurfaces Operating in the Visible

“…Furthermore, AR metasurfaces can deliver optimized transmission efficiency across multiple wavelengths, ideal for AMO applications where multiple wavelengths over 100 nm apart (but with small bandwidths) [ 10 ] need to be controlled simultaneously on the same photonic chip. Si metasurfaces that have been applied to Rb atoms, [ 5 ] and Ta 2 O 5 or TiO 2 ‐Damascene metasurfaces [ 16 ] that are being explored for Sr cold‐atom applications [ 17 ] benefit from the multi‐dielectric metasurface design paradigm (see Supporting Information).…”

“…We then showcase anti‐reflective metalenses at 461 nm. This wavelength is important for its use in Sr magneto‐optical traps, [ 17 ] while the divergent lens function employed here could be useful in coupling on‐chip light with small volumes to free space, [ 23 ] or as Petzval correctors in metalens doublets, [ 19 ] further advancing on‐chip atom‐photonics. Each batch contains five metalenses with diameter $$D\ = \ 500{\mathrm{\ \mu m}}$$ and focal lengths $$f\ = \ - ( {5,\ 2.5,\ 1,\ 0.75,{\mathrm{\ and\ }}0.5{\mathrm{\ mm}}} )$$; or numerical apertures $${\mathrm{NA\ }} \cong \ ( {0.05,\ 0.1,\ 0.2,\ 0.32,\ 0.45} )$$.…”

“…Metasurfaces with high efficiencies at multiple wavelengths, fabricated on the same photonic chip, in a single or a few fabrication steps, are critical for AMO applications. [ 17 ] Improved off‐axis transmission should help in cascading multiple metasurfaces; light incident on the metasurface cascade that becomes off‐axis between multiple metasurfaces would still need to transmit with high efficiency through the device.…”