High Resolution Brillouin Sensing of Micro-Scale Structures

• Main Authors: Atiyeh Zarifi, Birgit Stiller, Moritz Merklein, Benjamin J. Eggleton
• Format: Article
• Language: English
• Published: MDPI AG 2018-12-01
• Series: Applied Sciences
• Subjects: stimulated Brillouin scattering; distributed sensing; BOCDA; photonic waveguides
• Online Access: https://www.mdpi.com/2076-3417/8/12/2572

Brillouin distributed measurement techniques have been extensively developed for structural health monitoring using fibre optic nerve systems. The recent advancement in the spatial resolution capabilities of correlation-based Brillouin distributed technique have reached the sub-mm regime, making this approach a suitable candidate for monitoring and characterizing integrated photonic devices. The small dimension associated with the short length of these devices&#8212;on the order of the cm- and mm-scale&#8212;requires high sensitivity detection techniques and sub-mm spatial resolution. In this paper, we provide an overview of the different Brillouin sensing techniques in various micro-scale structures such as photonic crystal fibres, microfibres, and on-chip waveguides. We show how Brillouin sensing is capable of detecting fine transverse geometrical features with the sensitivity of a few nm and also extremely small longitudinal features on the order of a few hundreds of <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="sans-serif">&#956;</mi> <mi mathvariant="normal">m</mi> </mrow> </semantics> </math> </inline-formula>. We focus on the technique of Brillouin optical correlation domain analysis (BOCDA), which enables such high spatial resolution for mapping the opto-acoustic responses of micro-scale waveguides.