19 February 2011 Broad-band high-efficiency optoacoustic generation using a novel photonic crystal-metallic structure
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Proceedings Volume 7899, Photons Plus Ultrasound: Imaging and Sensing 2011; 78992C (2011); doi: 10.1117/12.876012
Event: SPIE BiOS, 2011, San Francisco, California, United States
Abstract
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.
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Yunbo Guo, Hyoung Won Baac, Sung-Liang Chen, Theodore B. Norris, L. Jay Guo, "Broad-band high-efficiency optoacoustic generation using a novel photonic crystal-metallic structure", Proc. SPIE 7899, Photons Plus Ultrasound: Imaging and Sensing 2011, 78992C (19 February 2011); doi: 10.1117/12.876012; https://doi.org/10.1117/12.876012
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KEYWORDS
Ultrasonography

Photonic crystals

Pulsed laser operation

Polymers

Acoustics

Transducers

Gold

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