Integrated optics design concepts applied to high frequency ultrasound detection

A novel application of polymer waveguide microring resonator for high-frequency ultrasound detection is presented. The device consists of a microring optical resonator that is coupled to a straight optical waveguide which serves as both input and output ports. Acoustic waves irradiating the ring waveguide induce strain that causes a change in the effective refractive index of optical waves propagating along the ring. The sharp wavelength dependence of the high Q-factor resonator enhances the optical response to the acoustic strain. High sensitivity has been demonstrated experimentally in the detection of broadband ultrasound pulses from a 10MHz transducer. WDM methods are proposed to extend the technique into an array of microrings for ultrasound imaging applications.