The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Namkyoo Park - One of the best experts on this subject based on the ideXlab platform.
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magnetic field enhancement beyond the Skin Depth limit
Proceedings of SPIE the International Society for Optical Engineering, 2010Co-Authors: Jonghwa Shin, Namkyoo ParkAbstract:Electric field enhancement has been actively studied recently and many metallic structures that are capable of locally enhancing electric field have been reported. The Babinet's principle can be utilized, especially in the form of Booker's extension, to transform the known electric field enhancing structures into magnetic field enhancing structures. The authors explain this transformation process and discuss the regime in which this principle breaks down. Unless the metals used can be well approximated with a perfect electric conductor model, the principle's predictions fail to hold true. Authors confirm this aspect using numerical simulations based on realistic material parameters for actual metals. There is large discrepancy especially when the structural dimensions are comparable or less than the Skin-Depth at the wavelength of interest. An alternative way to achieve magnetic field enhancement is presented and the design of a connected bow-tie structure is proposed as an example. FDTD simulation results confirm the operation of the proposed structure.
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extraordinary magnetic field enhancement with metallic nanowire role of surface impedance in babinet s principle for sub Skin Depth regime
Physical Review Letters, 2009Co-Authors: Sathish M Kumar, Jonghwa Shin, Namkyoo ParkAbstract:We propose and analyze the ‘‘complementary’’ structure of a metallic nanogap, namely, the metallic nanowire for magnetic field enhancement. A huge enhancement of the field up to a factor of 300 was achieved. Introducing the surface impedance concept, we also develop and numerically confirm a new analytic theory which successfully predicts the field enhancement factors for metal nanostructures. Compared to the predictions of the classical Babinet principle applied to a nanogap, an order of magnitude difference in the field enhancement factor was observed for the sub-Skin-Depth regime nanowire.
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terahertz field enhancement by a metallic nano slit operating beyond the Skin Depth limit
Nature Photonics, 2009Co-Authors: Hyeongryeol Park, D J Park, Jihun Kang, O K Suwal, S S Choi, P C M Planken, Gunsik Park, Namkyoo Park, Q-han ParkAbstract:The effect of a tiny gap in a metal substrate on incident terahertz radiation in the regime where the gap's dimensions are smaller than the metal's Skin-Depth are investigated. The results and theoretical analysis show that the gap acts as a capacitor charged by light-induced currents, and dramatically enhances the local electric field.
Stefan Franzen - One of the best experts on this subject based on the ideXlab platform.
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optical properties of indium tin oxide and fluorine doped tin oxide surfaces correlation of reflectivity Skin Depth and plasmon frequency with conductivity
Journal of Alloys and Compounds, 2002Co-Authors: Scott H Brewer, Stefan FranzenAbstract:Variable angle reflectance FTIR was used to investigate the reflectance of thin films of either indium tin oxide (ITO) or fluorine-doped tin oxide (SFO) on glass substrates in the mid-IR. The reflectance was observed to depend on the incident angle, wavenumber, and the polarization used. The Drude model and the Fresnel equations for reflection at a single dielectric boundary were used to interpret these results in terms of the conductivity, reflectivity, Skin Depth, and plasmon frequency of the metal oxides. The Skin Depth of thin film ITO electrodes was found to depend on the sheet resistance linearly, while the reflectance varied according to the square root of the sheet resistance. The method shows that an optical probe can be used to determine the electrical properties of metal oxide films in a noninvasive approach.
Scott H Brewer - One of the best experts on this subject based on the ideXlab platform.
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optical properties of indium tin oxide and fluorine doped tin oxide surfaces correlation of reflectivity Skin Depth and plasmon frequency with conductivity
Journal of Alloys and Compounds, 2002Co-Authors: Scott H Brewer, Stefan FranzenAbstract:Variable angle reflectance FTIR was used to investigate the reflectance of thin films of either indium tin oxide (ITO) or fluorine-doped tin oxide (SFO) on glass substrates in the mid-IR. The reflectance was observed to depend on the incident angle, wavenumber, and the polarization used. The Drude model and the Fresnel equations for reflection at a single dielectric boundary were used to interpret these results in terms of the conductivity, reflectivity, Skin Depth, and plasmon frequency of the metal oxides. The Skin Depth of thin film ITO electrodes was found to depend on the sheet resistance linearly, while the reflectance varied according to the square root of the sheet resistance. The method shows that an optical probe can be used to determine the electrical properties of metal oxide films in a noninvasive approach.
Zubin Jacob - One of the best experts on this subject based on the ideXlab platform.
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photonic Skin Depth engineering universal spin momentum locking of light conference presentation
Proceedings of SPIE, 2017Co-Authors: Saman Jahani, Zubin JacobAbstract:Here, we surpass the diffraction limit of light by a new class of all-dielectric artificial materials that are lossless. This overcomes one of the fundamental challenges of light confinement in metamaterials and plasmonics: metallic loss. Our approach relies on controlling the optical momentum of evanescent waves as opposed to conventional photonic devices which manipulate propagating waves. This leads to a counterintuitive confinement strategy for electromagnetic waves across the entire spectrum. We introduce two distinct photonic design principles that can ideally lead to sub-diffraction light confinement without metal. They are i) relaxed total internal reflection and ii) photonic Skin-Depth engineering. We present initial experimental results on a CMOS compatible platform that prove the enhanced confinement of our all-dielectric metamaterial design.
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photonic Skin Depth engineering
Journal of The Optical Society of America B-optical Physics, 2015Co-Authors: Saman Jahani, Zubin JacobAbstract:Recently, we proposed a paradigm shift in light confinement strategy showing how relaxed total internal reflection and photonic Skin-Depth engineering can lead to sub-diffraction waveguides without metal [Optica1, 96 (2014)10.1364/OPTICA.1.000096OPTIC82334-2536]. Here, we show that such extreme-Skin-Depth (e-skid) waveguides can counterintuitively confine light better than the best-case all-dielectric design of high index silicon waveguides surrounded by vacuum. We also establish analytically that figures of merit related to light confinement in dielectric waveguides are fundamentally tied to the Skin Depth of waves in the cladding, a quantity surprisingly overlooked in dielectric photonics. We contrast the propagation characteristics of the fundamental mode of e-skid waveguides and conventional waveguides to show that the decay constant in the cladding is dramatically larger in e-skid waveguides, which is the origin of sub-diffraction confinement. We also propose an approach to verify the reduced photonic Skin Depth in experiment using the decrease in the Goos–Hanschen phase shift. Finally, we provide a generalization of our work using concepts of transformation optics where the photonic Skin-Depth engineering can be interpreted as a transformation on the momentum of evanescent waves.
Q-han Park - One of the best experts on this subject based on the ideXlab platform.
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Strong coupling between terahertz nano slot antennas separated by sub-Skin Depth barriers
2011 International Conference on Infrared Millimeter and Terahertz Waves, 2011Co-Authors: H. R. Park, Y. M. Bahk, J. Bravo-abad, Q-han Park, F. J. Garcia-vidalAbstract:We show that sub-Skin Depth nanoscale barriers separating two vertically aligned slot antennas can strongly modulate their resonance features. Our findings have fundamental implications for the sensitive nano-particle detections using long wavelength light.
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terahertz field enhancement by a metallic nano slit operating beyond the Skin Depth limit
Nature Photonics, 2009Co-Authors: Hyeongryeol Park, D J Park, Jihun Kang, O K Suwal, S S Choi, P C M Planken, Gunsik Park, Namkyoo Park, Q-han ParkAbstract:The effect of a tiny gap in a metal substrate on incident terahertz radiation in the regime where the gap's dimensions are smaller than the metal's Skin-Depth are investigated. The results and theoretical analysis show that the gap acts as a capacitor charged by light-induced currents, and dramatically enhances the local electric field.
