GHz photoacoustic signal detection by a pump-probe system

Photoacoustic imaging (PAI) has enabled the high-resolution imaging of biological samples without reliance on external contrast agents. However, conventional photo- acoustic (PA) resolution in the axial direction is dependent on the maximum-detectable frequency of the ultrasound transducer, thereby limiting axial resolution to micrometers. Here, we present GHz detection of a PA signal that can potentially enhance the achievable resolution in PAI, previously limited by the detection bandwidth of ultrasound transducers. Our experimental setup shows that GHz detection of the PA signals is achievable via pump-probe imaging setups, which can enhance the axial resolution of PAI by orders of magnitude.