Waveguide-integrated and portable optomechanical magnetometer

Fernando Gotardo; Benjamin J. Carey; Hamish Greenall; Glen I. Harris; Erick Romero; Douglas Bulla; Elizabeth M. Bridge; James S. Bennett; Scott Foster; Warwick P. Bowen

arXiv · 2307.15229

Waveguide-integrated and portable optomechanical magnetometer

Fernando Gotardo·Benjamin J. Carey·Hamish Greenall·Glen I. Harris·Erick Romero·Douglas Bulla·Elizabeth M. Bridge·James S. Bennett·Scott Foster·Warwick P. Bowen

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Abstract

Optomechanical magnetometers enable highly sensitive magnetic field sensing. However, all such magnetometers to date have been optically excited and read-out either via free space or a tapered optical fiber. This limits their scalability and integrability, and ultimately their range of applications. Here, we present an optomechanical magnetometer that is excited and read out via a suspended optical waveguide fabricated on the same silicon chip as the magnetometer. Moreover, we demonstrate that thermomechanical noise limited sensitivity is possible using portable electronics and laser. The magnetometer employs a silica microdisk resonator selectively sputtered with a magnetostrictive film of galfenol (FeGa) which induces a resonant frequency shift in response to an external magnetic field. Experimental results reveal the retention of high quality-factor optical whispering gallery mode resonances whilst also demonstrating high sensitivity and dynamic range in ambient conditions. The use of off-the-shelf portable electronics without compromising sensor performance demonstrates promise for applications.

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Fernando Gotardo, Benjamin J. Carey, Hamish Greenall, Glen I. Harris, Erick Romero, Douglas Bulla, Elizabeth M. Bridge, James S. Bennett, Scott Foster, Warwick P. Bowen. 2023-07-27. Waveguide-integrated and portable optomechanical magnetometer. https://arxiv.org/abs/2307.15229

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