Ultrasound sensing and imaging based on whispering-gallery-mode (wgm) microresonators

An ultrasound imaging system, comprising:

• an acoustic transducer to transmit ultrasound pulses;
• an acoustic probe array including at least one optical whispering gallery mode resonator for sensing acoustic signals, at least one coupling waveguide having a first end and a second end opposite the first end, and a polymer encasing the optical whispering gallery mode resonator, the polymer having a convex upper boundary engineered to enhance acoustic focus on the optical whispering gallery mode resonator;
• a light source coupled to the first end of the coupling waveguide;
• and
• a light detector coupled to the second end of the coupling waveguide,
• wherein the resonator and the coupling waveguide each have higher refractive indices than a refractive index of the polymer, the at least one coupling waveguide is optically coupled to the optical whispering gallery mode resonator of at least one sensor, the at least one coupling waveguide is spaced apart from the optical whispering gallery mode resonator to which it is coupled by a separation gap, and the polymer encasing the optical whispering gallery mode resonator to which the at least one coupling waveguide is coupled also encases a portion of the coupling waveguide and fills the separation gap.