Heidelberg 2015 – scientific programme

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A: Fachverband Atomphysik

A 21: Ultra-cold plasmas and Rydberg systems II (with Q)

A 21.2: Talk

Wednesday, March 25, 2015, 11:15–11:30, C/kHS

Imaging of Microwave Fields with sub-100 µm Resolution in Vapor Cells — •Andrew Horsley, Guan-Xiang Du, and Philipp Treutlein — University of Basel, Swizterland

Microwave devices form an essential part of modern technology, finding application, e.g., in telecommunications and scientific instrumentation. We have developed a technique for imaging microwave magnetic fields using alkali vapor cells, detecting microwaves through Rabi oscillations driven on atomic hyperfine transitions. This could prove transformative in the design, characterisation, and debugging of microwave devices, as there are currently no established microwave imaging techniques. We present results from a new imaging system which provides spatial resolutions of 40−100 µm, an order of magnitude improvement from our previous proof-of-principle setup. More importantly, our vapor cell allows imaging of fields as close as 150 µm above structures, through the use of extremely thin external cell walls. This is crucial in allowing us to take practical advantage of our high spatial resolution, as feature sizes in near-fields are on the order of the distance from their source. We demonstrate our system through the imaging of microwave fields above a selection of microwave devices.

Our spatial resolution and approach distance are now sufficient for characterising a range of real world devices at fixed frequencies. However, the development of a broadband imaging technique is essential for wider applications. We also present progress on a frequency-tunable setup, allowing us to image microwaves at any frequency, from sub-GHz to 10s of GHz.