3,831 research outputs found
Transmission of Slow Light through Photonic Crystal Waveguide Bends
The spectral dependence of a bending loss of cascaded 60-degree bends in
photonic crystal (PhC) waveguides is explored in a slab-type
silicon-on-insulator system. Ultra-low bending loss of (0.05+/-0.03)dB/bend is
measured at wavelengths corresponding to the nearly dispersionless transmission
regime. In contrast, the PhC bend is found to become completely opaque for
wavelengths range corresponding to the slow light regime. A general strategy is
presented and experimentally verified to optimize the bend design for improved
slow light transmission.Comment: 4 pages, 3 figures; submitted to Optics Letter
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Mode degeneration in bent photonic crystal fiber study by using the finite element method
The development of highly dispersive lower and higher order cladding modes and their degeneration with respect to the fundamental core mode in a bent photonic crystal fiber is rigorously studied by use of the full-vectorial finite element method. It is shown that changes in the bending radius can modify the modal properties of large-area photonic crystal fibers, important for a number of potential practical applications
Isotropic Band Gaps and Freeform Waveguides Observed in Hyperuniform Disordered Photonic Solids
Recently, disordered photonic media and random textured surfaces have
attracted increasing attention as strong light diffusers with broadband and
wide-angle properties. We report the first experimental realization of an
isotropic complete photonic band gap (PBG) in a two-dimensional (2D) disordered
dielectric structure. This structure is designed by a constrained-optimization
method, which combines advantages of both isotropy due to disorder and
controlled scattering properties due to low density fluctuations
(hyperuniformity) and uniform local topology. Our experiments use a modular
design composed of Al2O3 walls and cylinders arranged in a hyperuniform
disordered network. We observe a complete PBG in the microwave region, in good
agreement with theoretical simulations, and show that the intrinsic isotropy of
this novel class of PBG materials enables remarkable design freedom, including
the realization of waveguides with arbitrary bending angles impossible in
photonic crystals. This first experimental verification of a complete PBG and
realization of functional defects in this new class of materials demonstrates
their potential as building blocks for precise manipulation of photons in
planar optical micro-circuits and has implications for disordered acoustic and
electronic bandgap materials
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Design of bent photonic crystal fiber supporting a single polarization
In this work, it is shown that the differential loss between the TE- and TM-polarized fundamental modes in a highly birefringent photonic crystal fiber (PCF) can be enhanced by bending the fiber. As a result, a design approach for single-mode single-polarization operation has been developed and is discussed. A rigorous full-vectorial H-field-based finite element approach, which includes the conformal transformation and the perfectly matched layer, is used to determine the single-polarization properties of such a highly birefringent PCF by exploiting its differential bending losses
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