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arXiv · 2408.12350

Integrating high-precision and fringe-scale displacement sensing using heterodyne cavity-tracking

Shreevathsa Chalathadka Subrahmanya·Christian Darsow-Fromm·Oliver Gerberding
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Abstract

We present a heterodyne stabilized cavity-based interferometer scheme that can serve as a compact and high-sensitivity displacement sensor with a fringe-scale operating range. The technique, in principle, can reach a sub-femtometer noise floor and an operating range on the order of one laser wavelength at $\lambda \approx 1\,\mu m$. With our current experimental setup, we achieve a sensitivity of about $260 fm/\sqrt{\mathrm{Hz}}$ at $1\,Hz$ and $46 fm/\sqrt{\mathrm{Hz}}$ at around $130\,Hz$. By probing a length actuated cavity, we demonstrate six orders of magnitude of dynamic range for displacement measurement, reaching a maximum motion of $0.15\,\mu m$. The tracking bandwidth and displacement range are limited by analog effects in the signal digitization and are extendable in the future.

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Shreevathsa Chalathadka Subrahmanya, Christian Darsow-Fromm, Oliver Gerberding. 2024-08-22. Integrating high-precision and fringe-scale displacement sensing using heterodyne cavity-tracking. https://doi.org/10.1364/oe.540189

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