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We study the role played by the indefinite weight function a(x) on the existence of positive solutions to the problem    −div (|∇u| p−2 ∇u) = λa(x)|u| p−2 u + b(x)|u| γ−2 u, x ∈ Ω, ∂u ∂n = 0, x ∈ ∂Ω, where Ω is a smooth bounded domain in R n , b changes sign, 1 < p < N, 1 < γ < Np/(N − p) and γ = p. We prove that (i) if Ω a(x) dx = 0 and b satisfies(More)
We introduce a plasmonic waveguide system, based on a plasmonic analogue of electromagnetically induced transparency, which supports a subwavelength slow-light mode, and exhibits a small group velocity dispersion. The system consists of a periodic array of two metal-dielectric-metal (MDM) stub resonators side-coupled to a MDM waveguide. Decreasing the(More)
Transfer printing is an exceptionally sophisticated approach to assembly and micro-/ nanofabrication that relies on a soft, elastomeric 'stamp' to transfer solid, micro-/ nanoscale materials or device components from one substrate to another, in a large-scale, parallel fashion. The most critical control parameter in transfer printing is the strength of(More)
A reconstruction theory for intensity diffraction tomography (I-DT) has been proposed that permits reconstruction of a weakly scattering object without explicit knowledge of phase information. We investigate the I-DT reconstruction problem assuming an incident (paraxial) spherical wave and scanning geometries that employ fixed source-to-object distances.(More)
We review some of the recent research activities on plasmonic devices based on metal-dielectric-metal (MDM) stub resonators for manipulating light at the nanoscale. We first introduce slow-light subwavelength plasmonic waveguides based on plasmonic analogues of periodically loaded transmission lines and electromagnetically induced transparency. In both(More)
SUMMARY The extended model concept links migration velocity analysis and waveform inversion. This abstract presents a method to solve a partially linearized version of the full waveform inversion problem with model extension. Linearization separates the model of the earth into the smooth long scale background model and the short scale model. Extended(More)
SUMMARY Migration velocity analysis (MVA) is an approach to solve a partially linearized variant of the waveform inversion problem, i.e. linear in short scales, nonlinear in long scales. The linear inversion part is often approximated by migration in practice , which is only adjoint of linearized Born modeling operator. In this abstract, we derive the(More)
The widely used least-squares approach to seismic inversion may fail due to insufficient data spectrum. The model extension modification to least-squares inversion can eliminate this full bandwidth requirement. For linearized extended modeling about smooth background parameters, a geometric-optics based analysis explains the increased robustness of extended(More)
We introduce compact wavelength-scale slit-based structures for coupling free space light into metal-dielectric-metal (MDM) subwave-length plasmonic waveguides. We first show that for a single slit structure the coupling efficiency is limited by a trade-off between the light power coupled into the slit, and the transmission of the slit-MDM waveguide(More)