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.
Bibliographical noteFunding Information:
We thank D. Cassettari, Y. Arita, M. Facchin, F. Gasparoli, J. Nylk, P. Rodríguez-Sevilla and P. Wijesinghe for technical assistance and useful discussions, and acknowledge funding from the Leverhulme Trust, UK Research Project Grant RPG-2017-197 . Research data supporting this publication can be accessed at https://doi.org/10.17630/4c8eb422-8204-4a3f-ab84-3630070dff2d
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering