Highly sensitive detection of photo-thermal transient stress by a sub-nanosecond pump probe with surface plasmon resonance

Photoacoustic microscopy (PAM) has attracted increasing attention for non-invasive functional imaging in biomedicine and biomedical studies. The surface plasmon resonance (SPR) sensor is a potential acoustical detector with high sensitivity and wide bandwidth for use in high-resolution 3D PAM. In this study, we investigated a simple Kretschmann SPR sensor, demonstrating highly sensitive stress detection in the sub-nanosecond timescale by directly inducing photo-thermal transient stress. To do this, we designed and used a sub-nanosecond pump probe system. The SPR sensor clearly detected the transient response from the thermal elastic effect, while a simple pump-probe sensor without SPR did not detect it. Our experimental results demonstrate a simple SPR sensor that can detect stress with high sensitivity and sub-nanosecond time resolution. This technique could be used in high-resolution 3D PAM by mounting a small biomedical sample on the sensor.