In this paper, we suggest the design of wavelength tunable, polarization-sensitive optical nanoswitches based on plasmonic spheroidal core-shell nanoparticles. Using a quasi-static approximation, we derive closed-form expressions for short and open circuit conditions, which respectively provide extremely high and low permittivity values at optical frequencies. Owing to the anisotropic nature of spheroidal particles, the analysis are performed in longitudinal and transversal polarizations, where the electric field of the impinging wave is along the major and minor axes of the spheroid, respectively. The derived formulas analytically elucidate this anisotropy, which has been implied by different short and open circuit conditions for two states of polarization. Our results show that by exploiting eccentricity in the spheroidal core-shells (i.e. compared to the spherical core-shells), the switching conditions can be transferred to infrared (IR) and ultraviolet (UV) frequencies, in longitudinal and transversal polarizations, respectively. Finally, the effective permittivity of the core-shell is extracted analytically using the concept of internal homogenization, which gains insight into the optical response of particle. Our analyses pave the way towards realizing tunable and polarization dependent components in UV, optical and IR frequencies for sensing and nanocircuitry applications. © 2018 IOP Publishing Ltd.

Chirality plays an essential role in life, providing unique functionalities to a wide range of biomolecules, chemicals, and drugs, which makes chiral sensing and analysis critically important. The wider application of chiral sensing continues to be constrained by the involved chiral signals being inherently weak. To remedy this, plasmonic and dielectric nanostructures have recently been shown to offer a viable route for enhancing weak circular dichroism (CD) effects, but most relevant studies have thus far been ad hoc, not guided by a rigorous analytical methodology. Here, we report the first analytical treatment of CD enhancement and extraction from a chiral biolayer placed on top of a nanostructured substrate. We derive closed-form expressions of the CD and its functional dependence on the background-chiroptical response, substrate thickness and chirality, as well as on the optical chirality and intensity enhancement provided by the structure. Our results provide key insights into the trade-offs that are to be accommodated in the design and conception of optimal nanophotonic structures for enhancing CD effects for chiral molecule detection. Based on our analysis, we also introduce a practical, dielectric platform for chiral sensing featuring large CD enhancements while exhibiting vanishing chiroptical background noise. © 2018 American Chemical Society.

Self-organized criticality emerges in dynamical complex systems driven out of equilibrium and characterizes a wide range of classical phenomena in physics, geology, and biology. We report on a quantum coherence-controlled selforganized critical transition observed in the light localization behavior of a coherence-driven nanophotonic configuration. Our system is composed of a gain-enhanced plasmonic heterostructure controlled by a coherent drive, in which photons close to the stopped-light regime interact in the presence of the active nonlinearities, eventually synchronizing their dynamics. In this system, on the basis of analytical and corroborating full-wave Maxwell-Bloch computations, we observe quantum coherence-controlled self-organized criticality in the emergence of light localization arising from the synchronization of the photons. It is associated with two first-order phase transitions: one pertaining to the synchronization of the dynamics of the photons and the second pertaining to an inversionless lasing transition by the coherent drive. The so-Attained light localization, which is robust to dissipation, fluctuations, and many-body interactions, exhibits scale-invariant power laws and absence of finely tuned control parameters. We also found that, in this nonequilibrium dynamical system, the effective critical "temperature" of the system drops to zero, whereupon one enters the quantum self-organized critical regime. Copyright © 2018 The Authors, some rights reserved.

We demonstrate that a non-reciprocal, time-variant fiber cavity can operate above the "fundamental" time-bandwidth limit (TBL) of reciprocal structures by more than two orders of magnitude. © 2018 The Author(s).