dc.contributor.authorGao, Fei
dc.contributor.authorFeng, Xiaohua
dc.contributor.authorZhang, Ruochong
dc.contributor.authorLiu, Siyu
dc.contributor.authorDing, Ran
dc.contributor.authorKishor, Rahul
dc.contributor.authorZheng, Yuanjin
dc.identifier.citationGao, F., Feng, X., Zhang, R., Liu, S., Ding, R., Kishor, R., et al. (2017). Single laser pulse generates dual photoacoustic signals for differential contrast photoacoustic imaging. Scientific Reports, 7, 626-.en_US
dc.description.abstractPhotoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent signal amplitude. An analytical model is derived to describe the generation of the dual photoacoustic pulses, incorporating Gruneisen saturation and thermal diffusion effect, which is experimentally proved. Lastly, an alternate of LDPA technique using quasi-CW laser excitation is also introduced and demonstrated for both super-contrast in vitro and in vivo imaging. Compared with existing nonlinear PA techniques, the proposed LDPA nonlinear effect could enable a much broader range of potential applications.en_US
dc.format.extent12 p.en_US
dc.relation.ispartofseriesScientific Reportsen_US
dc.rights© 2017 The Author(s) (Nature Publishing Group). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/en_US
dc.subjectImaging and sensingen_US
dc.titleSingle laser pulse generates dual photoacoustic signals for differential contrast photoacoustic imagingen_US
dc.typeJournal Article
dc.contributor.schoolSchool of Electrical and Electronic Engineeringen_US
dc.description.versionPublished versionen_US

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