Nonlinear photoacoustics for measuring the nonlinear optical absorption coefficient.
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.
Yelleswarapu
Chandra S
CS
Department of Physics, University of Massachusetts Boston, 100 Morrissey Blvd, Boston, MA 02125, USA. Chandra.yelleswarapu@umb.edu
Kothapalli
Sri-Rajasekhar
SR