© 2019 Optical Society of America
The detection of ultrasound via optical resonators is conventionally performed by tuning a continuous-wave (CW) laser to the linear slope of the resonance and monitoring the intensity modulation at the resonator output. While intensity monitoring offers the advantage of simplicity, its sensitivity is often limited by the frequency noise of the CW laser. In this work, we develop an alternative CW technique that can significantly reduce measurement noise by monitoring variations in the phase, rather than intensity, at the resonator output. In our current implementation, which is based on a balanced Mach–Zehnder interferometer for phase detection, we demonstrate a 24-fold increase in the signal-to-noise ratio of the detected ultrasound signal over the conventional, intensity-monitoring approach.[Read more…]
Fig. – Signals detected using the IM and PM interrogation methods with an optical power of 0.1 mW. In the PM measurement, the OPD was set to zero to maximize the SNR.
Lucas RiobĂł, Yoav Hazan, Francisco Veiras, MarĂa Garea, Patricio Sorichetti, and Amir Rosenthal. Optics Letters Vol. 44, Issue 11, pp. 2677-2680 (2019) •https://doi.org/10.1364/OL.44.002677
© 2019 Optical Society of America