Highly sensitive optical microresonator sensors for photoacoustic imaging

We present novel concave Fabry Perot (FP) sensor arrays for photoacoustic imaging which were fabricated using a high-precision inkjet printing approach to produce the cavity and employed physical vapor deposition to form the dielectric mirrors. Our concave FP cavity design provides excellent beam confinement within the cavity enabling high finesse and thus high sensitivity to be achieved. Two such concave sensors are evaluated in terms of their sensitivity and acoustic bandwidth. A 66 mu m thick concave sensor is shown to provide a noise equivalent pressure (NEP) of 85 Pa and an acoustic bandwidth of 16 MHz, and can potentially be used as a sensitive broadband sensor for superficial imaging. A 250 mu m thick sensor with an NEP of 12 Pa and acoustic bandwidth of 4 MHz was also developed for deep tissue imaging applications.