264 research outputs found
All-optical switching, bistability, and slow-light transmission in photonic crystal waveguide-resonator structures
We analyze the resonant linear and nonlinear transmission through a photonic crystal waveguide sidecoupled
to a Kerr-nonlinear photonic crystal resonator. First, we extend the standard coupled-mode theory
analysis to photonic crystal structures and obtain explicit analytical expressions for the bistability thresholds
and transmission coefficients which provide the basis for a detailed understanding of the possibilities associated
with these structures. Next, we discuss limitations of standard coupled-mode theory and present an
alternative analytical approach based on the effective discrete equations derived using a Green’s function
method. We find that the discrete nature of the photonic crystal waveguides allows a geometry-driven enhancement
of nonlinear effects by shifting the resonator location relative to the waveguide, thus providing an
additional control of resonant waveguide transmission and Fano resonances. We further demonstrate that this
enhancement may result in the lowering of the bistability threshold and switching power of nonlinear devices
by several orders of magnitude. Finally, we show that employing such enhancements is of paramount importance
for the design of all-optical devices based on slow-light photonic crystal waveguides
A near-field study on the transition from localized to propagating plasmons on 2D nano-wedges
In this manuscript we report on a near-feld study of two-dimensional
plasmonic gold nano-wedges using electron energy loss spectroscopy in
combination with scanning transmission electron microscopy, as well as
discontinuous Galerkin time-domain computations. With increasing nano-wedge
size, we observe a transition from localized surface plasmons on small
nano-wedges to non-resonant propagating surface plasmon polaritons on large
nano-wedges. Furthermore we demonstrate that nano-wedges with a groove cut can
support localized as well as propagating plasmons in the same energy range
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