We fabricate multimode polymer optical waveguides with circular graded-index (GI) cores which are aligned in parallel at desired positions using the Mosquito method. In the Mosquito method, three-dimensional wiring pa...
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We fabricate multimode polymer optical waveguides with circular graded-index (GI) cores which are aligned in parallel at desired positions using the Mosquito method. In the Mosquito method, three-dimensional wiring patterns can be formed with a simple process. However, the core position is likely to deviate from the designed position because of multiple fabrication factors. Hence, in this paper, the dominant parameters to influence on the core height in the cladding are investigated both theoretically and experimentally. In particular, a linear relationship between the core height and the needle-tip height is confirmed with theoretical fluid analysis. Using this relationship, we succeeded in fabricating a waveguide in which the maximum variation of the core height from the designed value is controlled to be less than 10 mu m. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
We investigate the energy transfer of surface plasmon polaritons (SPPs) based on adiabatic passage in a non-Hermitian waveguide composed of three coupled graphene sheets. The SPPs can completely transfer between two o...
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We investigate the energy transfer of surface plasmon polaritons (SPPs) based on adiabatic passage in a non-Hermitian waveguide composed of three coupled graphene sheets. The SPPs can completely transfer between two outer waveguides via the adiabatic dark mode as the waveguides are lossless and the coupling length is long enough. However, the loss of graphene can lead to breakdown of adiabatic transfer schemes. By utilizing the coupled mode theory, we propose three approaches to cancel the nonadiabatic coupling by adding certain gain or loss in respect waveguides. Moreover, the coupling length of waveguide is remarkably decreased. The study may find interesting application in optical switches on a deep-subwavelength scale.
In this work, we propose an innovative strategy for obtaining functional objects employing a light-activated three-dimensional (3D) printing process without affecting the materials' printability. In particular, a ...
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In this work, we propose an innovative strategy for obtaining functional objects employing a light-activated three-dimensional (3D) printing process without affecting the materials' printability. In particular, a dye is a necessary ingredient in a formulation for a digital light processing 3D printing method to obtain precise and complex structures. Here, we use a photoluminescent dye specifically synthesized for this purpose that enables the production of 3D printed waveguides and splitters able to guide the luminescence. Moreover, copolymerizing the dye with the polymeric network during the printing process, we are able to maintain the solvatochromic properties of the dye toward different solvents in the printed structures, enabling the development of solvents' polarity sensors.
A set of coupled integral equations is presented based on Love's and Schelkunoff's field equivalence principles. According to Love's equivalence principle and the boundary conditions, a general form of the...
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A set of coupled integral equations is presented based on Love's and Schelkunoff's field equivalence principles. According to Love's equivalence principle and the boundary conditions, a general form of the Poggio-Miller-Chang-Harrington-Wu formulation is applied for modeling the waveguide cavities containing composite structures. The structures are discretized using the higher order polynomial basis functions, whose orders are adaptively adjusted for accurately modeling current distributions in this kind of strong near-field coupling and resonance problems. Moreover, the integral equations for the apertures involving the waveguide ports, each of which is terminated by a semi-infinite waveguide, are established according to Schelkunoff's equivalence principle and the boundary conditions. Because the free-space Green's function as well as the spatial discretization-based basis functions cannot be applied to semi-infinite waveguides we employ waveguide eigenfunctions as the basis functions for the outer surface of an aperture. These coupled integral equations are then solved numerically using the method of moments accelerated by the parallel computing techniques. Comparisons with two well-developed software products demonstrate the accuracy and efficiency of the proposed method.
We propose and demonstrate an efficient method combining proton exchange with dry etching for the fabrication of low-loss bend channel waveguides in lithium niobate (LN) thin film. Our proposed method introduces the c...
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We propose and demonstrate an efficient method combining proton exchange with dry etching for the fabrication of low-loss bend channel waveguides in lithium niobate (LN) thin film. Our proposed method introduces the chemical etching caused by F+ ion to increase the etching rate. Our fabricated straight and bent channel waveguides have a trapezoid cross section with a top width of similar to 1.0 mu m, a height of similar to 900 nm, and a slope of similar to 20 degrees with respect to the vertical direction. To the best of our knowledge, this is the largest etching depth but with a small slope reported up to now. Mode intensity distributions and insertion losses were measured at 1.55 mu m wavelength and bending losses were deduced. The results show that our fabricated bent channel waveguide with a radius of 20 mu m can achieve low bending losses of 0.455 dB/90 degrees and 0.488 dB/90 degrees for the fundamental quasi-TE (qTE) and quasi-TM (qTM) modes, respectively. Compared with the fabrication methods reported so far, our method can realize a faster etching rate and a larger etching depth while maintaining a high etching quality. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
We numerically simulate novel planar plasmonic waveguides and notch filters with excellent guiding and rejection of terahertz (THz) waves with super subwavelength confinement. Our design is based on spoof surface plas...
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We numerically simulate novel planar plasmonic waveguides and notch filters with excellent guiding and rejection of terahertz (THz) waves with super subwavelength confinement. Our design is based on spoof surface plasmon polaritons-surface plasmon polaritons with a frequency that has been tuned using patterned conductive surfaces. We find that by using patterns of periodically arranged spiral-shaped units, the dispersion characteristics can be engineered at will by tuning the parameters of the spirals. We find that the resulting plasmonic waveguides have much lower asymptotic frequencies and much tighter terahertz field confinement when compared with conventional rectangular-grooved plasmonic waveguides. We show it is passible to design a structure with lateral dimensions that are only 25% the size of the conventional spoof surface plasmon polariton waveguides but with the same asymptotic frequency. Finally, we combined this architecture with broadband couplers to design an ultrawideband low-pass filter with sharp roll-off (cut-off frequency at 1.29 THz) and low insertion loss (<3 dB). Furthermore, by introducing double ring resonators based on spiral-shaped units, a planar plasmonic notch filter with rejection of more than 17 dB between 0.97 and 0.99 THz is demonstrated. The proposed waveguides and notch filters may have great potential applications in the promising terahertz integrated plasmonic circuits and systems.
In this paper, we employed optical waveguides in a silicon rod base structure to realize AND, OR logical operation simultaneously based on two-dimensional photonic crystals. All of the structure is composed of silicon...
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In this paper, we employed optical waveguides in a silicon rod base structure to realize AND, OR logical operation simultaneously based on two-dimensional photonic crystals. All of the structure is composed of silicon rods. Employing silicon rods of different radii as defect rods in optical waveguide filtered the desired wavelength. We utilized two similar waveguides as our input bits and two waveguides as AND and OR outputs. The overall footprint of the proposed device is 60m(2) and hence is very compact. The time responses of device are about 0.5ps and hence in conjunction with the mentioned characteristics suggest the use of the device for computational applications. The electric field distribution is obtained by the finite-difference time-domain method. In this paper, the logic state of 1' and 0' at output port is defined as the transmission is around 1' and less than 0.25, respectively. The compact size of the proposed structure and the materials used make the proposed device suitable for optical integrated circuits.
In this paper, we propose a semi-analytical isogeometric analysis(S-IGA) approach in the twist space to investigate the dispersive properties in helical thread waveguides, which combines the advantages of the spectral...
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In this paper, we propose a semi-analytical isogeometric analysis(S-IGA) approach in the twist space to investigate the dispersive properties in helical thread waveguides, which combines the advantages of the spectral approach and IGA. The convergence and accuracy of the proposed method are discussed, by comparing S-IGA results with reference solutions. Additionally, the analytical expression of axial offset wavenumbers is derived to explain the difference of spectrograms between the Cartesian and twisted systems. In order to illustrate the effectiveness of the proposed method, some dispersion curves of elastic wave propagation in helical thread waveguides are presented for a wide range of thicknesses and tortuosities. (C) 2017 Published by Elsevier B.V.
The coupling strength between two parity-time (PT) symmetric resonators determines whether the PT phase is broken or not. Here we investigate the scenario that two optical waveguides are spatially curved so that they ...
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The coupling strength between two parity-time (PT) symmetric resonators determines whether the PT phase is broken or not. Here we investigate the scenario that two optical waveguides are spatially curved so that they switch periodically between unbroken and broken PT phases. We show that the existence of locally broken PT phase does not necessarily render a broken phase to waves propagating inside. Criteria are proposed to characterize the collective dynamics of wave near the Brillouin zone (BZ) edge, toward the cases of a totally broken phase, a partially broken phase, or a totally unbroken phase. We also discuss the characteristics of two special kinds of exceptional points (EPs) at the BZ edge, and show that their field patterns are displaced by half a period with each other. Full-wave numerical simulation proves our analysis. Potential applications especially these associated with EPs are discussed. This study helps us to understand how the locally PT-symmetric related eigenstate influences the globally collective dynamics of wave in spatially periodic configuration. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
We consider a time-harmonic wave problem, appearing, for example, in water-wave theory, in acoustics, or in electromagnetism, in a setting such that the analysis reduces to the study of a 2D waveguide problem with a N...
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We consider a time-harmonic wave problem, appearing, for example, in water-wave theory, in acoustics, or in electromagnetism, in a setting such that the analysis reduces to the study of a 2D waveguide problem with a Neumann boundary condition. The geometry is symmetric with respect to an axis orthogonal to the direction of propagation of waves. Moreover, the waveguide contains one branch of finite length. We analyze the behavior of the complex scattering coefficients R, T as the length of the branch increases, and we show how to design geometries where nonreflectivity (R = 0, vertical bar T vertical bar = 1), perfect reflectivity (vertical bar R vertical bar = 1, T = 0), or perfect invisibility (R = 0, T = 1) holds. Numerical experiments illustrate the different results.
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