Chamanzar, M. et al. Nat. Commun. 10, 92 (2019).

A major challenge of optical imaging is that most biological tissues scatter light, which in many cases precludes light delivery beyond a few millimeters. Chamanzar et al. have developed a unique approach for steering and confining light within scattering samples by using ultrasound. This approach works because the applied acoustic waves change the local density and therefore the refractive index within the sample. The researchers demonstrated the use of acousto-optic confinement to generate optical waveguides by creating regions of high refractive index flanked by low-index regions. They further showed that the method can steer light through 240-μm-thick mouse brain slices. The promise of this approach is that it can be used to form desired light patterns within tissues, for advanced deep tissue imaging applications.