We model numerically the reshaping of a weak probe pulse propagating in an absorptive, optically dense, persistent spectral hole burning medium under conditions of slow group velocity. Saturated holes are burned in wa...
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We model numerically the reshaping of a weak probe pulse propagating in an absorptive, optically dense, persistent spectral hole burning medium under conditions of slow group velocity. Saturated holes are burned in waveguide geometry by illumination in the transverse direction with low absorption, whereas the probing is carried out in longitudinal wave guiding directions with high absorption. We show that by choosing optimum hole spectrum, the Gaussian probe pulse may be delayed by several times its original duration, while overall pulse shape distortion is less than 1% and average energy loss is less than 10%. (C) 2007 Elsevier B.V. All rights reserved.
We investigate guided modes in the asymmetric waveguide structure with a left-handed material （LHM） layer surrounded by air and metal. A graphical method is proposed to determine the guided modes. New properties of ...
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We investigate guided modes in the asymmetric waveguide structure with a left-handed material （LHM） layer surrounded by air and metal. A graphical method is proposed to determine the guided modes. New properties of the oscillating and surface guided modes, such as absence of the fundamental mode, coexistence of the oscillating and surface guided modes, fast attenuation of the surface guided modes, and mode degeneracy, are analyzed in detail. We also investigate dispersive characteristics of the metal-LHM- air optical waveguide. The propagation constant increases with decreasing slab thickness for the first-order oscillating mode, which is different from that in traditional metal-cladding waveguides.
A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is *** method synthesizes the three-dimensional field solution by using Fourier transform techniques based ...
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A coupled-mode method for three-dimensional acoustic propagation and scattering in two-dimensional waveguides is *** method synthesizes the three-dimensional field solution by using Fourier transform techniques based on a sequence of two-dimensional problems,each of which is solved by a numerical model recently developed by Luo et al.[***.29(2012)014302].Numerical results indicate that the present model is remarkably accurate,and thus can serve as benchmark against other numerical *** addition,this model can be applied to realistic problems,and can also be used to analyze horizontal refraction in some range-dependent waveguides in reality,such as the continental shelf environment,ridge-like bathymetry,and underwater trenches.
A method to measure the end-output coupling efficiencies between silicon wire waveguides(SWWs)and optical fibers is proposed and *** end-output coupling efficiency is calculated through four measured counting rates ba...
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A method to measure the end-output coupling efficiencies between silicon wire waveguides(SWWs)and optical fibers is proposed and *** end-output coupling efficiency is calculated through four measured counting rates based on the correlated photon pair generation in the *** provides a way to investigate and optimize the coupling processes at the input and output end of the optical waveguides separately.
Lithium niobate(LiNbO_(3),LN)channel and ridge waveguides have been successfully fabricated by He ion implantation,which has energy of 500 keV and fluence of 1.5×10^(16)ions/cm^(2) and is combined with lithograph...
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Lithium niobate(LiNbO_(3),LN)channel and ridge waveguides have been successfully fabricated by He ion implantation,which has energy of 500 keV and fluence of 1.5×10^(16)ions/cm^(2) and is combined with lithography and the precise diamond dicing *** refractive index profile of the annealed LN planar waveguide was *** propagation loss of the channel waveguide with a width of 10μm and that of the ridge waveguides with widths of 25μm and 15μm were investigated by the end-face coupling *** our work,the factors that affect the waveguide properties of channel and ridge waveguides were revealed.
Electromagnetic mode profile shaping would be a very useful technique, with applications including in accelerator science and data transmission. Two methods are proposed: one varying the permittivity and the other usi...
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Electromagnetic mode profile shaping would be a very useful technique, with applications including in accelerator science and data transmission. Two methods are proposed: one varying the permittivity and the other using a wire medium. By the use of Mathieu functions, we demonstrate a flatter, a triangular and a peakier profile. The first two may be used to manipulate longer particle bunches, while the last could be used on shorter bunches and in data transmission. It is also demonstrated how further improvements can be achieved by going beyond Mathieu functions.
The large velocity of electromagnetic waves makes the design of waveguide structures such as couplers and delay lines at radio frequencies (RFs) prohibitively large for chip-scale implementation. In contrast, acoustic...
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The large velocity of electromagnetic waves makes the design of waveguide structures such as couplers and delay lines at radio frequencies (RFs) prohibitively large for chip-scale implementation. In contrast, acoustic waves have velocities that are many orders of magnitude smaller. Thus, with the use of acoustic waves, RF waveguides become possible. In this article, the waveguiding of sub-1-GHz surface acoustic waves (SAWs) on 128 degrees Y-cut lithium niobate (LiNbO3) is examined with demonstrations of straight waveguides, waveguide bends, and coupled waveguides. Furthermore, an electroacoustic variable phase shifter based on an SAW waveguide on a bonded 128 degrees Y-cut LiNbO3 on silicon is demonstrated. Finally, an all-acoustic bidirectional RF phased array front end is demonstrated. The structures shown in this work can be implemented in commercial SAW foundries resulting in low-cost compact realizations of SAW microwave signal processing structures.
A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations sh...
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A hybrid plasmonic waveguide, consisting of two dielectric nanowires symmetrically put at the opposite corner angles of a rhombic metM, is proposed and numerically analyzed by the finite-element method. Simulations show that the present waveguide can achieve the millimeter propagation distance （1244 μm） and deep subwavelength mode area （5.5 × 10-3 μm2）, simultaneously. Compared with the previous hybrid waveguides based on cylinder nanowires or fiat films, the rhombie corner angles enable our waveguide to achieve both longer propagation distance and smaller mode area. This is due to the enhanced coupling between the dielectric guided mode in nanowires and the surface plasmon polariton mode at rhombic surface. Furthermore, the extreme confinement near the rhombic corner angles can strengthen the light-matter interaction greatly and make the present waveguide useful in many applications, such as nonlinear photonics, high-quality nanolazers and nanophotonic waveguides.
Planar optical waveguides in single crystals of KNbOs were fabricated by MeV B and He ion *** depth profiles of radiation damage in these waveguides were compared and analyzed by high resolution transmission electron ...
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Planar optical waveguides in single crystals of KNbOs were fabricated by MeV B and He ion *** depth profiles of radiation damage in these waveguides were compared and analyzed by high resolution transmission electron *** leaky waveguiding modes(TEo and TMo),which are due to implantation induced increase of rib and nc,were observed in 6.0 MeV B ion implantated waveguides with a dose of 1×10^(15)cm^(-2).
We characterize the process of soliton waveguides (SWGs) recording at 405 nm wavelength using pyroelectric effect in lithium niobate (LN) crystals. We experimentally study and discuss the influence of the input irradi...
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We characterize the process of soliton waveguides (SWGs) recording at 405 nm wavelength using pyroelectric effect in lithium niobate (LN) crystals. We experimentally study and discuss the influence of the input irradiance, the polarization of the signal beam, and the crystal temperature change on the waveguide writing time and mode-profile. These characteristics significantly change when changing the recording wavelength. The advantages of recording SWGs in LN by using blue-violet light and pyroelectric field are emphasised. The generation of radiation at 405 nm wavelength by inexpensive laser diodes, the fast recording at this wavelength, and the convenient way to produce a static electric field inside the crystal by heating it with few degrees leads to a next step in the soliton waveguides recording process with applications in 3D integrated optical circuits. (C) 2013 AIP Publishing LLC.
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