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arXiv · 2104.05136

Large evanescently-induced Brillouin scattering at the surrounding of a nanofibre

Fan Yang·Flavien Gyger·Adrien Godet·Jacques Chrétien·Li Zhang·Meng Pang·Jean-Charles Beugnot·Luc Thévenaz
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Abstract

Brillouin scattering has been widely exploited for advanced photonics functionalities such as microwave photonics, signal processing, sensing, lasing, and more recently in micro- and nano-photonic waveguides. So far, all the works have focused on the opto-acoustic interaction driven from the core region of micro- and nano-waveguides. Here we observe, for the first time, an efficient Brillouin scattering generated by an evanescent field nearby a sub-wavelength waveguide embedded in a pressurised gas cell, with a maximum gain coefficient of $18.90 \pm 0.17$ m$^{-1}$W$^{-1}$. This gain is 11 times larger than the highest Brillouin gain obtained in a hollow-core fibre and 79 times larger than in a standard single-mode fibre. The realisation of strong free-space Brillouin scattering from a waveguide benefits from the flexibility of confined light while providing a direct access to the opto-acoustic interaction, as required in free-space optoacoustics such as Brillouin spectroscopy and microscopy. Therefore, our work creates an important bridge between Brillouin scattering in waveguides, Brillouin spectroscopy and microscopy, and opens new avenues in light-sound interactions, optomechanics, sensing, lasing and imaging.

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Fan Yang, Flavien Gyger, Adrien Godet, Jacques Chrétien, Li Zhang, Meng Pang, Jean-Charles Beugnot, Luc Thévenaz. 2021-04-11. Large evanescently-induced Brillouin scattering at the surrounding of a nanofibre. https://doi.org/10.1038/s41467-022-29051-8

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