Various optical structures have been investigated for high-frequency optoacoustic generation via thermoelastic effect,
including metal films, mixture of polydimethylsiloxane (PDMS) and carbon black, two-dimensional (2-D) gold
nanostructure with PDMS film, etc. However, they suffer from either low light absorption efficiency which affects the
amplitude of generated ultrasound, or thick films that attenuate the amplitude and restrict its spectra bandwidth. Here we
propose a novel one-dimensional photonic crystal-metallic (PCM) structure, which can be designed to absorb 100%
optical energy of specific wavelengths in a total-internal-reflection geometry. The unique configuration enables us to
choose suitable polymer films on top of the metallic structure, which can act as an ideal ultrasound transmitter to
generate broad-band ultrasound with high conversion efficiency. Experimental results show that the PCM structure
generated several times stronger ultrasound pressure than our previously demonstrated 2-D gold nanostructures [Appl.
Phys. Lett. 89, 093901 (2006)]. Moreover, the generated ultrasound exhibited almost the same frequency spectrum as the
input laser pulse (duration width 6 ns). This shows that the PCM structure has great potential to generate broad-band
ultrasound signal. It is also important to mention that the simple PCM structure with the polymer film forms a
Fabry-Pérot resonator and can play a role of an ultrasound receiver, which provides a convenient method to construct a broad-band
and all-optical ultrasound transducer.