Two-photon polymerization-based polymer whispering-gallery-mode microresonators for photoacoustic microscopy (Conference Presentation)

Optical microresonator-based ultrasound sensors have shown great promise in photoacoustic imaging because of the broad bandwidth and the optical transparency for light-ultrasound integration. However, their applications are limited by the relatively low sensitivity compared to piezoelectric transducers. To address this limitation, we have developed a two-photon polymerization (TPP)-based technique to fabricate high-sensitivity, broadband microresonators for photoacoustic microscopy. Leveraging the 3D designability of TPP, we have optimized the microresonator structure, achieving a 1.2×10^5 Q-factor, 90% extinction ratio, >100 MHz bandwidth, and high sensitivity approaching that of piezoelectric transducers. The microresonator’s performance has been examined by imaging the mouse brain in vivo.