We report low-loss deep-etch AlGaAs optical waveguides fabricated with nitrogen plasma-assisted photoresist reflow. The simultaneous application of a nitrogen plasma and heat is used to reduce the line edge roughness ...
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We report low-loss deep-etch AlGaAs optical waveguides fabricated with nitrogen plasma-assisted photoresist reflow. The simultaneous application of a nitrogen plasma and heat is used to reduce the line edge roughness of patterned photoresist and limit the lateral spread of the photoresist patterns of submicron-scale waveguides. Comparison of the edge roughness of the etched sidewalls between the as-developed and smoothed photoresist etch samples show a reduction of the RMS roughness from 3.39 +/- 0.17 nm to 1.39 +/- 0.03 nm. The reduction in propagation loss is verified by measured waveguide loss as a function of waveguide widths. A 0.65-mu m wide waveguide with a modal area of 0.4 mu m(2) is fabricated with a propagation loss as low as 1.20 +/- 0.13 dB/cm for the transverse-electric mode. (C) 2014 Optical Society of America
The cross-section method is extended to the case of waveguides containing sharp metal edges. Such structures comprise strip lines, microstrip lines, and slot transmission lines. Relationships for eigenmode coupling co...
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The cross-section method is extended to the case of waveguides containing sharp metal edges. Such structures comprise strip lines, microstrip lines, and slot transmission lines. Relationships for eigenmode coupling coefficients in a section with parameters varying in the longitudinal direction are derived by passing to the limit: from a waveguide with smooth contour of the cross section to a waveguide with sharp edges. These relationships are applied to a single-mode strip line with conductor having variable width. It is shown that the obtained results agree with the results of the theory of microwave transmission lines.
New cinnamic acid type nonlinear-optical (NLO) photopolymers and their use in frequency doubling Cerenkov waveguides are reported. Cerenkov configurations are shown to be particularly appropriate for efficient second-...
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New cinnamic acid type nonlinear-optical (NLO) photopolymers and their use in frequency doubling Cerenkov waveguides are reported. Cerenkov configurations are shown to be particularly appropriate for efficient second-harmonic generation in NLO polymers. Analysis of Cerenkov waveguides in three-layer configurations allows optimization of their performance with respect to polymer layer thickness and substrate parameters. The NLO efficiencies predicted from the model and from independently determined NLO material parameters are qualitatively in agreement with the experimentally observed large Cerenkov NLO efficiency of 0.2% W-1 cm(-1). We show further that improved device performance results from novel four-layer waveguide configurations. (C) 1997 American Institute of Physics.
The recent discovery of room-temperature intrinsic single-photon emitters in silicon nitride (SiN)(1) provides a unique opportunity for seamless monolithic integration of quantum light sources with the well-establishe...
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The recent discovery of room-temperature intrinsic single-photon emitters in silicon nitride (SiN)(1) provides a unique opportunity for seamless monolithic integration of quantum light sources with the well-established SiN photonic platform. In this work, we successfully demonstrate the integration of intrinsic quantum emitters with planar waveguides composed of low-autofluorescence SiN and demonstrate single-photon emission coupling into the waveguide mode. The coupling of single-photon emission to the waveguide mode is confirmed by second-order autocorrelation measurements of light outcoupled off the photonic chip by grating couplers. Fitting the second-order autocorrelation histogram yields g((2))(0) = 0.15 +/- 0.09 without spectral filtering or background correction, the outcoupled photon rate derived from saturation measurements is found to be 6 x 10(3) counts per second. This demonstrates the first successful coupling of photons from monolithically integrated SiN intrinsic single-photon emitters with waveguides composed of the same material. The results of our work pave the way toward the realization of scalable, technology-ready quantum photonic integrated circuitry efficiently interfaced with solid-state quantum emitters.
In neutron optics, we analyse the propagation of slow (thermal) neutrons along a semi-infinite waveguide limited by a large repulsive potential (reminding the propagation of light along an optical fibre). We set an id...
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In neutron optics, we analyse the propagation of slow (thermal) neutrons along a semi-infinite waveguide limited by a large repulsive potential (reminding the propagation of light along an optical fibre). We set an ideal case of a straight empty two-dimensional semi-infinite waveguide limited by an infinitely repulsive potential (Dirichlet conditions on its boundaries). The neutron wave function is given through an integral representation involving the incoming wave with energyE, Green's function and certain functions defined on the boundaries. The latter functions follow from the Dirichlet conditions, thereby proposing a new formalism in neutron optics. We develop various approximations (through Fourier and Hilbert transforms) and numerical computations. We get: (a) the expected extinction of the incoming wave for very large penetration into the waveguide, (b) the generation of propagation modes and their number for suitably large penetration, asEincreases, (c) an estimate of the critical angle.
In a previous work, we reported a novel optical waveguide named silicon nanowire optical waveguide (SNOW), which consists of arrayed silicon nanowires acting like an effective-index medium. In this paper, we analyze b...
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In a previous work, we reported a novel optical waveguide named silicon nanowire optical waveguide (SNOW), which consists of arrayed silicon nanowires acting like an effective-index medium. In this paper, we analyze bend properties of the waveguide and show that small radii bends can be achieved in SNOW structures with low radiation losses. For bend radii of 5 and 2 mu m at a wavelength of 1550 nm, the radiation loss per 360 degrees turn is 5 x 10(-4) and 0.05 dB, respectively. Furthermore, we study the losses for changing the pitch between the nanowires and show that the loss behavior follows effective-index bulk waveguide approximation. Consequently, we show that the bending losses can be optimized by arranging the nanowires pitch size such that the density is higher in the inner side of the bend as compared with the outer side. Effects of wavelength and sidewall roughness on propagation loss are also investigated.
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.
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
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.
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