Slow light filters with MHz frequency resolution for enhancing the contrast in ultrasound-modulated optical tomography

Ultrasound-modulated optical tomography (UOT) is a promising method to go beyond the 5cm “hard depth” detection limit[1]. The principal idea of UOT is to use the acousto-optic effect, where the ultrasound shifts the frequency of the light. The resolution of UOT (∼ mm) is determined by the ultrasonic wave focus and duration, and the UOT contrast is determined by the optical properties of the tissue [2].