title: Nonlinear photoacoustics for measuring the nonlinear optical absorption coefficient.
abstract: We report a novel photoacoustic Z-scan (PAZ-scan) technique that combines the advantages offered by the conventional Z-scan method and the sensitivity of the photoacoustic detection. The sample is scanned through the focused laser beam and the generated photoacoustic signal is recorded using a 10 MHz focused ultrasound transducer. Since the signal strength is directly proportional to the optical absorption, PAZ-scan displays nonlinear behavior depicting the nonlinear optical absorption of the material. Among many advantages, our experiments on mouse blood show that PAZ-scan can potentially be used as a standard technique to calibrate contrast agents used in theranostics in general and photoacoustics in particular.
authors.affiliation: Department of Physics, University of Massachusetts Boston, 100 Morrissey Blvd, Boston, MA 02125, USA. Chandra.yelleswarapu@umb.edu
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Yelleswarapu
authors.forename: Sri-Rajasekhar
authors.initials: SR
authors.lastname: Kothapalli