arXiv subjects

Chetna Taneja

Publications and source records attributed to Chetna Taneja.

4 recordsLinked to original sources

arXiv2021

Experimental observation of transverse spin of plasmon polaritons in a single-crystalline silver nanowire

We report the experimental observation of the transverse spin and associated spin-momentum locking of surface plasmon polaritons (SPPs) excited in a plasmonic single crystalline silver nanowire (AgNW). In contrast to the SPPs excited in metal films, the electromagnetic field components of the evanescent SPP mode propagating along the long axis ($x$ axis) of the NW can decay along two longitudinal planes ($x$-$y$ and $x$-$z$ planes), resulting in two orthogonal transverse spin components ($s_z$ and $s_y$). Analysis of the opposite circular polarization components of the decaying SPP mode signal in the longitudinal plane ($x$-$y$) reveals spin dependent biasing of the signal and hence the existence of transverse spin component ($s_z$). The corresponding transverse spin density ($s_3$) in the Fourier plane reveals spin-momentum locking, where the helicity of the spin is dictated by the wave-vector components of the SPP evanescent wave. Further, the results are corroborated with three-dimensional numerical calculations. The presented results showcase how a chemically prepared plasmonic AgNW can be harnessed to study optical spins in evanescent waves, and can be extrapolated to explore sub-wavelength effects including directional spin coupling and optical nano-manipulation.

physics.optics↗

arXiv2021

Sub-Wavelength Plasmon Polaritons Channeling of Whispering Gallery Modes of Fluorescent Silica Microresonator

Herein, we report sub-wavelength propagation and directional out-coupling of whispering gallery modes (WGMs) of a fluorescent silica microsphere resonator mediated via plasmon polaritons in a single crystalline silver nanowire. Fluorescent spectral signatures of emission from the nanowire ends confirm efficient guiding of WGMs via nanowire plasmons. By employing Fourier plane optical microscopy, we reveal and quantify the directional fluorescence emission of WGMs from the ends of the nanowire. Given that the discussed geometry is self-assembled from a solution-phase, our results will find relevance in WGM-based soft-photonic platforms including miniaturized optical resonators and couplers.

physics.optics↗

arXiv2020

Plasmonic nanowire coupled to zero-dimensional nanostructures: A brief review

Metal nanowires and nanoparticles that facilitate surface plasmons are of contemporary interest in nanophotonics, thermoplasmonics and optoelectronics. They facilitate not only subwavelength light propagation and localization capabilities, but also provide an excellent platform for opto-thermal effects confined to volumes down to the nanoscale. This brief review article aims to provide an overview of a specific nanophotonic geometry: a plasmonic nanowire coupled to a zero-dimensional nanostructure. We discuss the methods to prepare such nano-architectures and review some interesting nanophotonic applications that arise out of it. We conclude with a discussion on some emerging research directions that can be facilitated by employing the coupled nanostructures.

physics.optics↗

arXiv2019

Dielectric microsphere coupled to a plasmonic nanowire: A self-assembled hybrid optical antenna

Hybrid mesoscale-structures that can combine dielectric optical resonances with plasmon-polaritons are of interest in chip-scale nano-optical communication and sensing. This experimental study shows how a fluorescent microsphere coupled to a silver nanowire can act as a remotely-excited optical antenna. To realize this architecture, self-assembly methodology is used to couple a fluorescent silica microsphere to a single silver nanowire. By exciting propagating surface plasmon polaritons at one end of the nanowire, remote excitation of the Stokes-shifted whispering gallery modes (WGMs) of the microsphere is achieved. The WGM-mediated fluorescence emission from the system is studied using Fourier plane optical microscopy, and the polar and azimuthal emission angles of the antenna are quantified. Interestingly, the thickness of the silver nanowires is shown to have direct ramifications on the angular emission pattern, thus providing a design parameter to tune antenna characteristics. Furthermore, by employing three-dimensional numerical simulations, electric near-fields of the gap-junction between the microsphere and the nanowire is mapped, and the modes of nanowire that couple to the microsphere is identified. This work provides a self-assembled optical antenna that combines dielectric optical resonances with propagating-plasmons and can be harnessed in hybrid nonlinear-nanophotonics and single-molecule remote sensing.

physics.optics↗