Modeling Optical Phase Conjugation of Ultrasonically Encoded Signals Utilizing Finite-Difference Time-Domain Simulations

Abstract

Strong scattering of light propagating through tissue limits the maximum focal depth of an optical wave, inhibiting the use of light in medical diagnostics and therapeutics. Turbidity suppression has been demonstrated utilizing phase conjugation with an ultrasound (US) generated guide star. The US beam is focused to a point in tissue inducing variations in the optical properties, thus modulating the optical signal. The detected wave-front is demodulated, conjugated and transmitted back into the tissue where it converges to the ultrasound’s focus. The technique is analyzed utilizing a Finite-Difference Time-Domain simulation to propagate the optical wave in a synthetic skin model.