Jacob T. Friedlein, Esther Baumann, Kimberly A. Briggman, Gabriel M. Colacion, Fabrizio R. Giorgetta, Daniel I. Herman, Nathan R. Newbury, Jeeseong Hwang, Ian R. Coddington, Kevin C. Cossel, Gabriel Ycas, Christopher S. Yung, Eli V. Hoenig, Edgar F. Perez
Spectrally-resolved photoacoustic imaging is a promising technique for label-free imaging in optically scattering materials. However, this technique often requires acquisition of a separate image at each wavelength of interest. This reduces imaging speeds and can cause errors if the sample changes between images acquired at different wavelengths. We demonstrate a solution to this problem by using dual-comb spectroscopy for photoacoustic measurements. This approach enables a photoacoustic measurement at thousands of wavelengths simultaneously. In this technique, two optical frequency combs are interfered on a sample and the resulting pressure wave is measured with an ultrasound transducer. This acoustic signal is processed in the frequency-domain to obtain an optical absorption spectrum. For a proof-of-concept demonstration, we measure the photoacoustic signals from polymers. The absorption spectra obtained from these measurements agree with those measured using a spectrophotometer. Improving the signal-to-noise ratio of the reported dual- comb photoacoustic spectrometer could enable high-speed spectrally-resolved photoacoustic imaging.