High speed determination of laser wavelength using Poincaré descriptors of speckle

Graham Bruce
Thursday 5 September 2019

Laura O’Donnell, Kishan Dholakia and Graham D. Bruce

Opt. Commun. 459, 124906 (2020) / arXiv: 1908.00665

Laser speckle can provide a powerful tool that may be used for metrology, for example measurements of the incident laser wavelength with a resolution beyond that which may be achieved in a commercial device. However, to realise highest resolution requires advanced multi-variate analysis techniques, which limit the acquisition rate of such a wavemeter. Here we show an arithmetically simple method to measure wavelength changes with dynamic speckle, based on a Poincarè descriptor of the speckle pattern. We demonstrate the measurement of wavelength changes at femtometer-level with a measurement time reduced by two orders of magnitude compared to the previous state-of-the-art, which offers promise for applications such as speckle-based laser wavelength stabilisation.

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