Simultaneous multi-channel ultrasound detection via optical phase modulated pulse interferometry (Conference Presentation)

In optical detection of ultrasound, resonators with high Q-factors are frequently used to maximize sensitivity. However, in order to perform parallel interrogation, conventional interferometric techniques require an overlap between the resonator spectra, which is difficult to achieve with high Q-factor resonators. In this work, a new method is developed for simultaneous interrogation of optical resonators with non-overlapping spectra. The method is based on a phase modulation scheme for pulse interferometry (PM-PI) and requires only a single photodetector and sampling channel per ultrasound detector. Using PM-PI, parallel ultrasound detection is demonstrated with four high Q-factor resonators.