Nonlinear photoacoustic generation by pump-probe excitation

Abstract

Photoacoustic technique has undergone major developments in recent decades. Most of current photoacoustic systems work in the linear range, in which the photoacoustic amplitude increases proportionally to the increasing of illuminating light power. The imaging sensitivity and contrast, however, in this case are limited due to stronger background signals from intrinsic chromophores in biological tissue. The current work investigates the advantages of nonlinear photoacoustic generation compared to linear signal, by using a single-wavelength pump-probe and nanosecond-scale two-pulse excitation scheme. The results show that nonlinearity induced by this scheme yields higher detection sensitivity and contrast.