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Single Nanoparticle Detection Using Far-field Emission of Photonic Molecule around the Exceptional Point.

Zhang N, Liu S, Wang K, Gu Z, Li M, Yi N, Xiao S, Song Q - Sci Rep (2015)

Bottom Line: In addition to typical mode splitting, we find that the far-field pattern of the PM is significantly changed.Taking a heteronuclear diatomic PM as an example, we demonstrate that a single nanoparticle, whose radius is as small as 1 nm to 7 nm, can be simply monitored through the variation of the far-field pattern.In addition, this research will illuminate new advances in single nanoparticle detection.

View Article: PubMed Central - PubMed

Affiliation: Integrated Nanoscience Lab, Department of Electrical and Information Engineering, Harbin Institute of Technology, Shenzhen, 518055, China.

ABSTRACT
Highly sensitive, label-free detection methods have important applications in fundamental research and healthcare diagnostics. To date, the detection of single nanoparticles has remained largely dependent on extremely precise spectral measurement, which relies on high-cost equipment. Here, we demonstrate a simple but very nontrivial mechanism for the label-free sizing of nanoparticles using the far-field emission of a photonic molecule (PM) around an exceptional point (EP). By attaching a nanoparticle to a PM around an EP, the main resonant behaviors are strongly disturbed. In addition to typical mode splitting, we find that the far-field pattern of the PM is significantly changed. Taking a heteronuclear diatomic PM as an example, we demonstrate that a single nanoparticle, whose radius is as small as 1 nm to 7 nm, can be simply monitored through the variation of the far-field pattern. Compared with conventional methods, our approach is much easier and does not rely on high-cost equipment. In addition, this research will illuminate new advances in single nanoparticle detection.

No MeSH data available.


Related in: MedlinePlus

The schematic picture of photonic molecule.The radiuses of left and right circles are R1 and r1, respectively. The inner boundary of annular ring is  and parameters are r0 = 0.56, ε = 0.16. R1 = 0.9985R, r1 = R, d1 = 0.8R, β1 = 0. The radius of nanoparticle is r2 positioned at the Azimuthal position β2 (here β2 = 0). The separation distance between nanoparticle and circular cavity is d2 = 0.015R.
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f1: The schematic picture of photonic molecule.The radiuses of left and right circles are R1 and r1, respectively. The inner boundary of annular ring is and parameters are r0 = 0.56, ε = 0.16. R1 = 0.9985R, r1 = R, d1 = 0.8R, β1 = 0. The radius of nanoparticle is r2 positioned at the Azimuthal position β2 (here β2 = 0). The separation distance between nanoparticle and circular cavity is d2 = 0.015R.

Mentions: Below, we take a heteronuclear diatomic PM as an example to illustrate the above analysis. Compared with the single cavity, PM supports modes with narrow linewidths, wide mode spacing, and greatly enhanced sensitivity to the changes in the dielectric constant of their environment3940. Importantly, the heteronuclear diatomic PM can be an optimal platform to generate the combination of high Q factor, high chirality, and unidirectional output41. Here, the chirality is different from the conventional chiral media and can be defined by the different components in the CW and CCW directions, following the equation3132. As illustrated in Fig. 1, the PM consists of a circular cavity and an annular cavity. The inner boundary of the annular cavity is a spiral shape that is defined in polar coordinates as. Below, we focus on the mode around kR = 4.3436, which corresponds to a wavelength of approximately 1.46 μm when R = 1 (fixed below). The target nanoparticle is positioned at the azimuthal position βj, and the separation distance between the nanoparticle and the circular cavity is d2. The radius of the nanoparticle is r2. Note that because the wavelength is much larger than the size of the scatter, the precise shape is not important in our system.


Single Nanoparticle Detection Using Far-field Emission of Photonic Molecule around the Exceptional Point.

Zhang N, Liu S, Wang K, Gu Z, Li M, Yi N, Xiao S, Song Q - Sci Rep (2015)

The schematic picture of photonic molecule.The radiuses of left and right circles are R1 and r1, respectively. The inner boundary of annular ring is  and parameters are r0 = 0.56, ε = 0.16. R1 = 0.9985R, r1 = R, d1 = 0.8R, β1 = 0. The radius of nanoparticle is r2 positioned at the Azimuthal position β2 (here β2 = 0). The separation distance between nanoparticle and circular cavity is d2 = 0.015R.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493635&req=5

f1: The schematic picture of photonic molecule.The radiuses of left and right circles are R1 and r1, respectively. The inner boundary of annular ring is and parameters are r0 = 0.56, ε = 0.16. R1 = 0.9985R, r1 = R, d1 = 0.8R, β1 = 0. The radius of nanoparticle is r2 positioned at the Azimuthal position β2 (here β2 = 0). The separation distance between nanoparticle and circular cavity is d2 = 0.015R.
Mentions: Below, we take a heteronuclear diatomic PM as an example to illustrate the above analysis. Compared with the single cavity, PM supports modes with narrow linewidths, wide mode spacing, and greatly enhanced sensitivity to the changes in the dielectric constant of their environment3940. Importantly, the heteronuclear diatomic PM can be an optimal platform to generate the combination of high Q factor, high chirality, and unidirectional output41. Here, the chirality is different from the conventional chiral media and can be defined by the different components in the CW and CCW directions, following the equation3132. As illustrated in Fig. 1, the PM consists of a circular cavity and an annular cavity. The inner boundary of the annular cavity is a spiral shape that is defined in polar coordinates as. Below, we focus on the mode around kR = 4.3436, which corresponds to a wavelength of approximately 1.46 μm when R = 1 (fixed below). The target nanoparticle is positioned at the azimuthal position βj, and the separation distance between the nanoparticle and the circular cavity is d2. The radius of the nanoparticle is r2. Note that because the wavelength is much larger than the size of the scatter, the precise shape is not important in our system.

Bottom Line: In addition to typical mode splitting, we find that the far-field pattern of the PM is significantly changed.Taking a heteronuclear diatomic PM as an example, we demonstrate that a single nanoparticle, whose radius is as small as 1 nm to 7 nm, can be simply monitored through the variation of the far-field pattern.In addition, this research will illuminate new advances in single nanoparticle detection.

View Article: PubMed Central - PubMed

Affiliation: Integrated Nanoscience Lab, Department of Electrical and Information Engineering, Harbin Institute of Technology, Shenzhen, 518055, China.

ABSTRACT
Highly sensitive, label-free detection methods have important applications in fundamental research and healthcare diagnostics. To date, the detection of single nanoparticles has remained largely dependent on extremely precise spectral measurement, which relies on high-cost equipment. Here, we demonstrate a simple but very nontrivial mechanism for the label-free sizing of nanoparticles using the far-field emission of a photonic molecule (PM) around an exceptional point (EP). By attaching a nanoparticle to a PM around an EP, the main resonant behaviors are strongly disturbed. In addition to typical mode splitting, we find that the far-field pattern of the PM is significantly changed. Taking a heteronuclear diatomic PM as an example, we demonstrate that a single nanoparticle, whose radius is as small as 1 nm to 7 nm, can be simply monitored through the variation of the far-field pattern. Compared with conventional methods, our approach is much easier and does not rely on high-cost equipment. In addition, this research will illuminate new advances in single nanoparticle detection.

No MeSH data available.


Related in: MedlinePlus