Fresnel Zone Plate Ring Waveguides for Improved Atom Interferometer Sensors

The sensitivity of an atomic interferometer is directly proportional to the area enclosed by the interferometer arms. This dependence is at odds with the aim of producing low Size, Weight, and Power (SWaP) sensor packages. Using atomic waveguides to maximise the enclosed area is a well-established technique for optimising these systems whilst reducing the overall size. We present a scheme for using Fresnel Zone Plates (FZPs) to produce smooth ring-shaped optical potentials to act as atomic waveguides and present a method for the loading of cold rubidium atoms into these rings. With the use of a shaped high-power 1064nm beam incident on our FZP, we produce the ring potential and, using an optical relay system, reimage it into our vacuum chamber. Both red and grey optical molasses are then utilised to cool the atoms to approximately 3.5μK (at a phase space density of 2.67×10^-4) for loading into our chosen ring-shaped waveguide of radius 0.5mm, waist size 10μm, and approximate depth 19.9μK. This work presents a key step towards the realisation of low SWaP, high sensitivity atom interferometer sensor packages.