37 research outputs found
Observation of emission from chaotic lasing modes in deformed microspheres: displacement by the stable orbit modes
By combining detailed imaging measurements at different tilt angles with
simulations of ray emission from prolate deformed lasing micro-droplets, we
conclude that the probability density for the lasing modes in a
three-dimensional dielectric microcavity must reside in the chaotic region of
the ray phase space. In particular, maximum emission from such chaotic lasing
modes is not from tangent rays emerging from the highest curvature part of the
rim. The laser emission is observed and calculated to be non-tangent and
displaced from the highest curvature due to the presence of stable orbits. In
this Letter we present the first experimental evidence for this phenomenon of
``dynamical eclipsing''.Comment: 4 figure
Curvature-induced radiation of surface plasmon polaritons propagating around bends
We present a theoretical study of the curvature-induced radiation of surface
plasmon polaritons (SPPs) propagating around bends at metal-dielectric
interfaces. We explain qualitatively how the curvature leads to distortion of
the phase front, causing the fields to radiate energy away from the
metal-dielectric interface. We then quantify, both analytically and
numerically, radiation losses and energy transmission efficiencies of SPPs
propagating around bends with varying radii- as well as sign-of-curvature.Comment: 9 pages, 8 figures, submitted to Physical Review
Methods for 3-D vector microcavity problems involving a planar dielectric mirror
We develop and demonstrate two numerical methods for solving the class of
open cavity problems which involve a curved, cylindrically symmetric conducting
mirror facing a planar dielectric stack. Such dome-shaped cavities are useful
due to their tight focusing of light onto the flat surface. The first method
uses the Bessel wave basis. From this method evolves a two-basis method, which
ultimately uses a multipole basis. Each method is developed for both the scalar
field and the electromagnetic vector field and explicit ``end user'' formulas
are given. All of these methods characterize the arbitrary dielectric stack
mirror entirely by its 2\times2 transfer matrices for s- and p-polarization. We
explain both theoretical and practical limitations to our method. Non-trivial
demonstrations are given, including one of a stack-induced effect (the mixing
of near-degenerate Laguerre-Gaussian modes) that may persist arbitrarily far
into the paraxial limit. Cavities as large as 50 \lambda are treated, far
exceeding any vectorial solutions previously reported.Comment: For high-quality figures, visit
http://darkwing.uoregon.edu/~noeckel/papers.ph
Bragg-induced orbital angular-momentum mixing in paraxial high-finesse cavities
Numerical calculation of vector electromagnetic modes of plano-concave
microcavities reveals that the polarization-dependent reflectivity of a flat
Bragg mirror can lead to unexpected cavity field distributions for nominally
paraxial modes. Even in a rotationally symmetric resonator, certain pairs of
orbital angular momenta are necessarily mixed in an excitation-independent way
to form doublets. A characteristic mixing angle is identified, which even in
the paraxial limit can be designed to have large values. This correction to
Gaussian theory is zeroth-order in deviations from paraxiality. We discuss the
resulting nonuniform polarization fields. Observation will require small
cavities with sufficiently high Q. Possible applications are proposed.Comment: Corrected typos in Fig. 2 and text. Added Journal Ref. For
higher-quality figures, see
http://darkwing.uoregon.edu/~noeckel/papers.php#xref3
Ray and wave chaos in asymmetric resonant optical cavities
Optical resonators are essential components of lasers and other
wavelength-sensitive optical devices. A resonator is characterized by a set of
modes, each with a resonant frequency omega and resonance width Delta
omega=1/tau, where tau is the lifetime of a photon in the mode. In a
cylindrical or spherical dielectric resonator, extremely long-lived resonances
are due to `whispering gallery' modes in which light circulates around the
perimeter trapped by total internal reflection. These resonators emit light
isotropically. Recently, a new category of asymmetric resonant cavities (ARCs)
has been proposed in which substantial shape deformation leads to partially
chaotic ray dynamics. This has been predicted to give rise to a universal,
frequency-independent broadening of the whispering-gallery resonances, and
highly anisotropic emission. Here we present solutions of the wave equation for
ARCs which confirm many aspects of the earlier ray-optics model, but also
reveal interesting frequency-dependent effects characteristic of quantum chaos.
For small deformations the lifetime is controlled by evanescent leakage, the
optical analogue of quantum tunneling. We find that the lifetime is much
shortened by a process known as `chaos-assisted tunneling'. In contrast, for
large deformations (~10%) some resonances are found to have longer lifetimes
than predicted by the ray chaos model due to `dynamical localization'.Comment: 4 pages RevTeX with 7 Postscript figure
Goos-Haenchen induced vector eigenmodes in a dome cavity
We demonstrate numerically calculated electromagnetic eigenmodes of a 3D dome
cavity resonator that owe their shape and character entirely to the
Goos-Haenchen effect. The V-shaped modes, which have purely TE or TM
polarization, are well described by a 2D billiard map with the Goos-Haenchen
shift included. A phase space plot of this augmented billiard map reveals a
saddle-node bifurcation; the stable periodic orbit that is created in the
bifurcation corresponds to the numerically calculated eigenmode, dictating the
angle of its "V". A transition from a fundamental Gaussian to a TM V mode has
been observed as the cavity is lengthened to become nearly hemispherical.Comment: 4 pages, 4 figure