Fiber-optic vibration sensors
Fiber Bragg gratings (FBGs) have previously found many applications as strain and vibration sensors and several commercial systems exist. Our group demonstrated that one can use an optical cavity written into a conventional single mode fiber to measure strain and vibration over a very large range of amplitudes and a massive frequency range - from static strain to medical ultrasound frequencies (over 6 MHz).
Their very high fidelity and extremely low noise permit their use as pickups for musical instruments and, specifically, for acoustic guitars . By fixing the fiber strain sensor to a vibrating part of the instrument's body, e.g., near the bridge of an acoustic guitar or on the headstock of a solid-body guitar, sound recordings were made and compared to those obtained with either piezoelectric pickups or with magnetic induction pickups. Paul Langlois of the Tragically Hip helped us with the demonstration of the prototype. (see also our youtube channel)
Ongoing research explores the use of these sensors in the characterization of acoustic properties of tissues and tissue phantoms in medical ultrasound imaging.
Paul Langlois playing the Photonic Guitar