A dispersion-varying tapered planar waveguide is designed to generate supercontinuum efficiently in the mid-infrared region. The rib waveguide of lead-silicate glass on silica is 1.8 cm long, consisting of a segment w...
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A dispersion-varying tapered planar waveguide is designed to generate supercontinuum efficiently in the mid-infrared region. The rib waveguide of lead-silicate glass on silica is 1.8 cm long, consisting of a segment with longitudinally increasing etch depth. The mechanism involves nonlinear soliton dynamics. The dispersion profile is shifted along the propagation distance, leading to continuous modification of the phase-matching condition for dispersive wave (DW) emission and enhancement of energy transfer efficiency between solitons and DWs. With low input pulse energy of 45 pJ, simulation demonstrates the generation of both broadband and flat near-octave spectrum spanning 1.3-2.5 mu m at the -20 dB level. (C) 2015 Optical Society of America
This work investigates the material birefringence in a polymer strip waveguide which originates from thermal stress during the fabrication process. The stress is estimated through a comprehensive numerical study based...
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This work investigates the material birefringence in a polymer strip waveguide which originates from thermal stress during the fabrication process. The stress is estimated through a comprehensive numerical study based on a realistic finite element model. The characteristics of birefringence are obtained in a generalized form and expressed by an empirical formula, which is applicable to various polymer materials. The developed formula can be employed to specify the photo-elastic birefringence of a polymer strip channel only by knowing the birefringence in its planar film. This will eliminate the necessity of extensive numerical analysis of thermal stress in such polymer waveguides, and accordingly help the management of stress-induced effects efficiently. (C)2015 Optical Society of America
Here we compare different nanoscale waveguiding geometries involving plasmonic materials for subdiffractive propagation at optical frequencies. Deriving closed-form analytical formulas to analyze the different structu...
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Here we compare different nanoscale waveguiding geometries involving plasmonic materials for subdiffractive propagation at optical frequencies. Deriving closed-form analytical formulas to analyze the different structures, we show how the presence of a plasmonic background may produce robust, highly confined guided wave propagation as compared with the dual setups involving plasmonic particles in a transparent background. Advantages and disadvantages of different scenarios for realizing right-handed and left-handed propagation in one-dimensional (1D) and two-dimensional (2D) waveguides are highlighted and discussed.
Electric and magnetic waveguides are considered in planar Dirac materials like graphene as well as their classical version for relativistic particles of zero mass and electric charge. We have assumed the displacement ...
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Electric and magnetic waveguides are considered in planar Dirac materials like graphene as well as their classical version for relativistic particles of zero mass and electric charge. We have assumed the displacement symmetry of the system along the y-direction, whose associated constant is k. We have also examined other symmetries relevant to each type of waveguide, magnetic or electric. waveguides with square profile have been worked out in detail to show up explicitly some of the most interesting features. For example, the classical region of confined motion of the electric case, for a fixed intensity, is bounded between k and -k, while in the magnetic case that region is symmetric in the energy and presents a gap (-k, k). Besides, in the quantum systems we have shown that there are edge states in the magnetic systems but they are missing in electric waveguides. We have also analysed scattering states and resonances which match with bound states for both waveguides. The classical scattering properties are also quite different in both types of waveguides. While the electric system has essentially one type of refraction of the incident electron, the magnetic system is much richer due to the Lorentz force.
In this paper, we analyze and simulate the lossless propagation of lightwaves in the active metal-semiconductor-metal plasmonic waveguides (MSMPWs) at the wavelength range of 1540-1560 nm using a quantum dot (QD) acti...
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In this paper, we analyze and simulate the lossless propagation of lightwaves in the active metal-semiconductor-metal plasmonic waveguides (MSMPWs) at the wavelength range of 1540-1560 nm using a quantum dot (QD) active medium. The Maxwell's equations are solved in the waveguide, and the required gains for achieving lossless propagation are derived. On the other hand, the rate equations in quantum dot active regions are solved by using the Runge-Kutta method, and the achievable optical gain is derived. The analyses results show that the required optical gain for lossless propagation in MSMPWs is achievable using the QD active medium. Also, by adjusting the active medium parameters, the MSMPWs loss can be eliminated in a specific bandwidth, and the propagation length increases obviously. (C) 2015 Optical Society of America
We explore a class of dielectrically loaded metallic waveguides capable of supporting negative index modes in the far infrared and terahertz regime. Principles of operation, modal structure and appropriate coupling sc...
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We explore a class of dielectrically loaded metallic waveguides capable of supporting negative index modes in the far infrared and terahertz regime. Principles of operation, modal structure and appropriate coupling schemes are analytically and numerically investigated. The extreme simplicity of the proposed design, along with the non-conventional and counter intuitive electromagnetic properties of this family of waveguides, makes these structures excellent candidates for the practical realization of negative index far infrared and terahertz devices with new and interesting functionalities. Generalizations and extensions of the suggested design are also discussed. (C) 2010 Optical Society of America
Issues relating to modal degeneracy in an equilateral triangular waveguide are herein treated. Specifically, it is determined precisely which cutoff frequencies can arise, the multiplicity of each such frequency is as...
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Issues relating to modal degeneracy in an equilateral triangular waveguide are herein treated. Specifically, it is determined precisely which cutoff frequencies can arise, the multiplicity of each such frequency is ascertained, and a procedure is developed which provides a prescription for finding all the modes associated with each of these frequencies. Such modes are degenerate in as much as they share the same propagation constant and are thus susceptible to mode coupling. As an added dividend, we characterize the family of harmonic series into which these frequencies naturally assemble. Just enough of the requisite number theory is appended to make this account reasonably self-contained.
Etching of amorphous Al2O3 and polycrystalline Y2O3 films has been investigated using an inductively coupled reactive ion etch system. The etch behaviour has been studied by applying various common process gases and c...
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Etching of amorphous Al2O3 and polycrystalline Y2O3 films has been investigated using an inductively coupled reactive ion etch system. The etch behaviour has been studied by applying various common process gases and combinations of these gases, including CF4/O-2, BCl3, BCl3/HBr, Cl-2, Cl-2/Ar and Ar. The observed etch rates of Al2O3 films were much higher than Y2O3 for all process gases except for Ar, indicating a much stronger chemical etching component for the Al2O3 layers. Based on analysis of the film etch rates and an investigation of the selectivity and patterning feasibility of possible mask materials, optimized optical channel-waveguide structures were fabricated in both materials. In Al2O3, channel waveguides were fabricated with BCl3/HBr plasma and using a standard resist mask, while in Y2O3, channel waveguides were fabricated with Ar and using either a resist or a sputter deposited Al2O3 mask layer. The etched structures in both materials exhibit straight sidewalls with minimal roughness and sufficient etch depths (up to 530 nm for Al2O3 and 250 nm for Y2O3) for defining waveguides with strong optical confinement. Using the developed etch processes, low additional optical propagation losses (on the order of 0.1 dB/cm) were demonstrated in single-mode ridge waveguides in both Al2O3 and Y2O3 layers at 1550 nm.
Germanosilicate glass waveguides were electrically poled using interdigitated electrodes. This poling resulted in a quasiphase-matched second-order susceptibility. Second-harmonic light was observed. Measured intensit...
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Germanosilicate glass waveguides were electrically poled using interdigitated electrodes. This poling resulted in a quasiphase-matched second-order susceptibility. Second-harmonic light was observed. Measured intensities were one to two orders of magnitude smaller than expected based on previous electric-field-induced second-harmonic (EFISH) generation studies with the same interdigitated electrodes, The dynamics of the EFISH signals were studied. Exponentially decaying signals suggest that through charge migration, via dielectric relaxation and electronic drift, a compromising field is established during the poling. This results in a weaker second-order susceptibility. (C) 1996 American Institute of Physics.
Simulation and experimental results of grating couplers composed of arrays of nanoholes are presented. The use of an array of holes instead of a conventional waveguide grating provides an additional degree of freedom ...
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Simulation and experimental results of grating couplers composed of arrays of nanoholes are presented. The use of an array of holes instead of a conventional waveguide grating provides an additional degree of freedom in the design of the coupler, thus enabling fabrication using the same photolithography mask and etching process as used for the silicon-on-insulator (SOI) waveguides. A grating coupler with coupling efficiency as high as 34% for coupling between the TE mode of the silicon nanophotonic wire waveguide and a single-mode optical fiber and with 3-dB bandwidth of 40 nm was fabricated. A theoretical model is presented, and 3-D finite-difference time-domain simulations are used to optimize the coupler design.
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