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Mie resonators for infrared meta-optics: Scalable, large area Se spheres on several substrates demonstrate the Mie-resonant response in the mid-infrared (MIR) spectral range. The size-tunable Mie resonances span the 2–16 μm spectral range for single isolated resonators and large area ensembles. It is capable of strong absorption up to 90% in ensembles of particles in a broad MIR range. In addition, the ultra-high-Q resonances arise in the case where Se Mie-resonators are coupled to low-loss epsilon-near-zero (ENZ) substrates. These findings demonstrate the enabling potential of amorphous Selenium as a versatile and tunable nanophotonic material that may open up avenues for on-chip MIR spectroscopy, chemical sensing, spectral imaging, and large area metasurface fabrication. Read more...
Nanowire-Nanoparticle system: switchable optical nano antenna (Optics Letters, 40, 1006-1009 (2015 )
Nanowire-nanoparticle system: The single system which is in hybrid formation of coupled single nanoparticle and single nanwire. This system can employ for single- and dual-directional out-coupling of light from NW-NP junction for plasmons. The SPPs excitation can be performed through glass-substrate and air-superstrate. Furthermore, we show NW-NP junction can influence the directionality of molecular-fluorescence emission, thus functioning as an optical antenna. The results discussed herein may have implications in realizing directional single-photon sources and quantum plasmon circuitry. Read more...
Serially coupled nanowire system: Propagation and localization of light at sub-wavelength scale is an important capability and a reliable solution which has great relevance in realizing the leading nanophotonic applications of light. In dielectric optics, diffraction of light has been a major hindrance to control light at nanoscale, but in recent years metallic nanostructures that support surface plasmons have opened up new avenues to propagate and localize light at subwavelength regime. This has led to tremendous interest in interaction of light with nanoscale plasmonic geometries such as silver nanowires (Ag-NW) that can be harnessed as circuit-element in a nanophotonic circuit. For such circuits to emerge, it is necessary to further develop and understand capability of plasmonic nanowires to perform various logical functions similar to circuit elements in electronics. Read more...
Plasmonic nano beam splitter (Appl. Phys. Lett. 101, 111111 (2012) )
Curved space plasmonics (Optics Letters, 40, 5234-5237, 2019)
Plasmonic elements based on curved surfaces: The propagation dynamics of surface plasmonic waves can be controlled by the curvature of the surface. Curvature-based effects have been observed in various systems such as electron wavefunctions in nanostructures and optical waves that are bound to curved thin dielectric guiding layers. The curvature of the surface acts as an effective potential that can alter the propagation dynamics of the surface waves. Such effects open up a new degree of freedom for controlling and manipulating surface waves, and in particular surface plasmons polaritons (SPPs), by curving the metal–dielectric boundary surface. SPPs are the coupled state of light and collective oscillations of free electrons at the metal–dielectric interface. Read More...
Dual channel advanced optical Fourier microscopy and spectroscopy system: The optical emission characteristics from individual nanostructures such as organic waveguides, plasmonic nanowires and 2D materials such as MoS2 can vary depending on the nature of interface on which they are grown or deposited. We constructed a dual-channel Fourier-plane microscopy, which is capable to study the directional emission characteristics of individual organic mesowires, Ag nanowires and MoS2 nanolayers through the glass substrate or air superstrate. Specifically, it is shown the ability of our microscope to quantitatively probe the radial and azimuthal angular spread in the waveguided PL from the distal ends of the mesowire across the interface without changing its position or orientation. Furthermore, from the guided PL spectral signatures, we show that the finesse of the waveguided Fabry-Perot resonance depends on whether the measurement was performed through the substrate or superstrate. To reveal the versatility of our microscope, we have quantified angular distribution of directional light scattering from the distal end of Ag nanowire at an interface, and angular distribution of excitonic emission from MoS2 nanolayers through a glass substrate. Our work highlights the capability of dual-channel Fourier microscope in quantifying the angular emission characteristics from individual optical antenna structures at an interface, and can be extrapolated to nonlinear organic nanophotonic regimes. Read more...
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