Plasmon enhanced photoacoustic generation from volumetric electromagnetic hotspots.

This work reports plasmon enhanced photoacoustic generation by using a three dimensional plasmonic absorber. The 3D plasmonic absorber comprises a thin polymer film on glass nanopillar arrays with nanogap-rich silver nanoislands. The 3D plasmonic absorber clearly shows 24.6 times higher enhancement of photoacoustic signals at an excitation wavelength of 630 nm than a simple polymeric absorber. The photoacoustic enhancement results from the volumetric electromagnetic field enhancement on a light-absorbing polymer through 3D plasmonic nanostructures. This novel photoacoustic absorber provides a new direction for highly efficient ultrasonic generation.