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Articles 1 - 5 of 5
Full-Text Articles in Physics
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. Casse, W. Lu, Y. Huang, E. Gultepe, L. Menon, S. Sridhar
Super-Resolution Imaging Using A Three-Dimensional Metamaterials Nanolens, B. Casse, W. Lu, Y. Huang, E. Gultepe, L. Menon, S. Sridhar
Srinivas Sridhar
Super-resolution imaging beyond Abbe's diffraction limit can be achieved by utilizing an optical medium or "metamaterial" that can either amplify or transport the decaying near-field evanescent waves that carry subwavelength features of objects. Earlier approaches at optical frequencies mostly utilized the amplification of evanescent waves in thin metallic films or metal-dielectric multilayers, but were restricted to very small thicknesses (⪡λ, wavelength) and accordingly short object-image distances, due to losses in the material. Here, we present an experimental demonstration of super-resolution imaging by a low-loss three-dimensional metamaterial nanolens consisting of aligned gold nanowires embedded in a porous alumina matrix. This composite …
Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier Casse, Ravinder Banyal, W. Lu, Y. Huang, Selvapraba Selvarasah, Mehmet Dokmeci, Srinivas Sridhar
Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier Casse, Ravinder Banyal, W. Lu, Y. Huang, Selvapraba Selvarasah, Mehmet Dokmeci, Srinivas Sridhar
Srinivas Sridhar
We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.
Dielectric Signatures Of Lattice Instabilities At 32k And 245k In $La_{2-Y}Sr_{Y}Mo_{4+X}$ (M=Cu,Ni) Cuprates And Nickelates, P. Parimi, N. Hakim, F. Chou, S. Cheong, S. Sridhar
Dielectric Signatures Of Lattice Instabilities At 32k And 245k In $La_{2-Y}Sr_{Y}Mo_{4+X}$ (M=Cu,Ni) Cuprates And Nickelates, P. Parimi, N. Hakim, F. Chou, S. Cheong, S. Sridhar
Srinivas Sridhar
New dielectric transitions are observed at common temperatures 32K and 245K, in isostructural $La_{2}CuO_{4+x}$ and $La_{5/3}Sr_{1/3}NiO_{4},$ that are signatures of local lattice (octahedral) instabilities. The present dielectric transitions reveal new aspects of the phase diagram of the perovskite cuprates and nickelates. They suggest that competition and coexistence of superconductivity with dielectricity occurs that is analogous to that between superconductivity and anti-ferromagnetism. These results also indicate that inhomogeneous electronic states, such as charge stripes and oxygen ordering, are strongly connected to underlying lattice instabilities.
Alternative Approach To All-Angle Negative Refraction In Two-Dimensional Photonic Crystals, Y. Huang, W. Lu, S. Sridhar
Alternative Approach To All-Angle Negative Refraction In Two-Dimensional Photonic Crystals, Y. Huang, W. Lu, S. Sridhar
Srinivas Sridhar
We show that with an appropriate surface modification, a slab of photonic crystal can be made to allow wave transmission within the photonic band gap. Furthermore, negative refraction and all-angle-negative-refraction (AANR) can be achieved by this surface modification in frequency windows that were not realized before in two-dimensional photonic crystals [C. Luo et al, Phys. Rev. B 65, 201104 (2002)]. This approach to AANR leads to new applications in flat lens imaging. Previous flat lens using photonic crystals requires object-image distance u + v less than or equal to the lens thickness d, u+v ∼ d. Our approach can be …
Correlations Among The Riemann Zeros: Invariance, Resurgence, Prophecy And Self-Duality, W. Lu, S. Sridhar
Correlations Among The Riemann Zeros: Invariance, Resurgence, Prophecy And Self-Duality, W. Lu, S. Sridhar
Srinivas Sridhar
We present a conjecture describing new long range correlations among the Riemann zeros leading to 3 principal features: (i) The spectral auto-correlation is invariant w.r.t. the averaging window. (ii) Resurgence occurs wherein the lowest zeros appear in all auto-correlations. (iii) Suitably defined correlations lead to predictions (prophecy) of new zeros. This conjecture is supported by analytical arguments and confirmed by numerical calculations using 10²² zeros computed by Odlyzko. The results lead to a self-duality of the Riemann spectrum similar to the quantum-classical duality observed in billiards.