83 research outputs found
Hyperuniform disordered phononic structures
We demonstrate the existence of large phononic band gaps in designed
hyperuniform (isotropic) disordered two-dimensional (2D) phononic structures of
Pb cylinders in epoxy matrix. The phononic band gaps in hyperuniform disordered
phononic structures are comparable to band gaps of similar periodic structures,
for both out-of-plane and in-plane polarizations. A large number of localized
modes is identified near the band edges, as well as, diffusive transmission
throughout the rest of the frequency spectrum. Very high-Q cavity modes for
both out-of-plane and in-plane polarizations are formed by selectively removing
a single cylinder out of the structure. Efficient waveguiding with almost 100%
transmission trough waveguide structures with arbitrary bends is also
presented. We expand our results to thin three-dimensional layers of such
structures and demonstrate effective band gaps related to the respective 2D
band gaps. Moreover, the drop in the Q factor for the three-dimensional
structures is not more than three orders of magnitude compared to the 2D ones
High-Q photonic crystal cavities in all-semiconductor photonic-crystal heterostructures
Photonic crystal cavities enable the realization of high Q-factor and low
mode-volume resonators, with typical architectures consisting of a thin
suspended periodically-patterned layer to maximize confinement of light by
strong index guiding. We investigate a heterostructure-based approach
comprising a high refractive index core and lower refractive index cladding
layers. Whilst confinement typically decreases with decreasing index contrast
between the core and cladding layers, we show that, counter-intuitively, due to
the confinement provided by the photonic band structure in the cladding layers,
it becomes possible to achieve Q-factors with only a small refractive
index contrast. This opens up new opportunities for implementing high Q-factor
cavities in conventional semiconductor heterostructures, with direct
applications to the design of electrically-pumped nano-cavity lasers using
conventional fabrication approaches
Optical cavities and waveguides in hyperuniform disordered photonic solids
Using finite difference time domain and band structure computer simulations,
we show that it is possible to construct optical cavities and waveguide
architectures in hyperuniform disordered photonic solids that are unattainable
in photonic crystals. The cavity modes can be classified according to the
symmetry (monopole, dipole, quadrupole,etc.) of the confined electromagnetic
wave pattern. Owing to the isotropy of the band gaps characteristic of
hyperuniform disordered solids, high-quality waveguides with freeform
geometries (e.g., arbitrary bending angles) can be constructed that have no
analogue in periodic or quasiperiodic solids. These capabilities have
implications for many photonic applications
Effects of Random Link Removal on the Photonic Band Gaps of Honeycomb Networks
We explore the effects of random link removal on the photonic band gaps of
honeycomb networks. Missing or incomplete links are expected to be common in
practical realizations of this class of connected network structures due to
unavoidable flaws in the fabrication process. We focus on the collapse of the
photonic band gap due to the defects induced by the link removal. We show that
the photonic band gap is quite robust against this type of random decimation
and survives even when almost 58% of the network links are removed
Thermal emission and absorption of radiation in finite inverted-opal photonic crystals
We study theoretically the optical properties of a finite inverted-opal photonic crystal. The light-matter interaction is strongly affected by the presence of the three-dimensional photonic crystal and the alterations of the light emission and absorption processes can be used to suppress or enhance the thermal emissivity and absorptivity of the dielectric structure. We investigate the influence of the absorption present in the system on the relevant band edge frequencies that control the optical response of the photonic crystal. Our study reveals that the absorption processes cause spectral broadening and shifting of the band edge optical resonances, and determine a strong reduction of the photonic band gap spectral range. Using the angular and spectral dependence of the band edge frequencies for stop bands along different directions, we argue that by matching the blackbody emission spectrum peak with a prescribed maximum of the absorption coefficient, it is possible to achieve an angle-sensitive enhancement of the thermal emission/absorption of radiation. This result opens a way to realize a frequency-sensitive and angle-sensitive photonic crystal absorbers/emitters. © 2005 The American Physical Society
Single photons on demand from 3D photonic band-gap structures
We describe a practical implementation of a (semi-deterministic) photon gun
based on stimulated Raman adiabatic passage pumping and the strong enhancement
of the photonic density of states in a photonic band-gap material. We show that
this device allows {\em deterministic} and {\em unidirectional} production of
single photons with a high repetition rate of the order of 100kHz. We also
discuss specific 3D photonic microstructure architectures in which our model
can be realized and the feasibility of implementing such a device using
ions that produce single photons at the telecommunication
wavelength of m.Comment: 4 pages, 4 EPS figure
Photonic band gap in isotropic hyperuniform disordered solids with low dielectric contrast
We report the first experimental demonstration of a TE-polarization photonic
band gap (PBG) in a 2D isotropic hyperuniform disordered solid (HUDS) made of
dielectric media with a index contrast of 1.6:1, very low for PBG formation.
The solid is composed of a connected network of dielectric walls enclosing
air-filled cells. Direct comparison with photonic crystals and quasicrystals
permitted us to investigate band-gap properties as a function of increasing
rotational isotropy. We present results from numerical simulations proving that
the PBG observed experimentally for HUDS at low index contrast has zero density
of states. The PBG is associated with the energy difference between
complementary resonant modes above and below the gap, with the field
predominantly concentrated in the air or in the dielectric. The intrinsic
isotropy of HUDS may offer unprecedented flexibilities and freedom in
applications (i. e. defect architecture design) not limited by crystalline
symmetries
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