25 research outputs found

    Dynamics of surface solitons at the edge of chirped optical lattices

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    We address soliton formation at the edge of chirped optical lattices imprinted in Kerr-type nonlinear media. We find families of power thresholdless surface waves that do not exist at other types of lattice interfaces. Such solitons form due to combined action of internal reflection at the interface, distributed Bragg-type reflection, and focusing nonlinearity. Remarkably, we discover that surfaces of chirped lattices are soliton attractors: Below an energy threshold, solitons launched well within the lattice self-bend toward the interface, and then stick to it.Comment: 13 pages, 4 figure

    Scattering of dipole-mode vector solitons: Theory and experiment

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    We study, both theoretically and experimentally, the scattering properties of optical dipole-mode vector solitons - radially asymmetric composite self-trapped optical beams. First, we analyze the soliton collisions in an isotropic two-component model with a saturable nonlinearity and demonstrate that in many cases the scattering dynamics of the dipole-mode solitons allows us to classify them as ``molecules of light'' - extremely robust spatially localized objects which survive a wide range of interactions and display many properties of composite states with a rotational degree of freedom. Next, we study the composite solitons in an anisotropic nonlinear model that describes photorefractive nonlinearities, and also present a number of experimental verifications of our analysis.Comment: 8 pages + 4 pages of figure

    Simulation model validation of two common i-line photoresists

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    In this paper we analyze the dissolution behavior of two common i-line resists (MEGAPOSIT SPR 955-CM and AZ MiR 701) and validate the experimental findings by generating simulation models and implementing them in simulation software. It is demonstrated that with the data provided by a Dissolution Rate Monitor (DRM) the quality of lithography simulation results can improve and can speed up process development and optimization. Different process conditions were investigated to evaluate the area of validity of the simulation model. Lithography simulation software packages LayoutLAB and Dr. LiTHO were used to verify the resist models

    Fast and highly accurate simulation of the printing behavior of EUV multilayer defects based on different models

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    This paper employs rigorous electromagnetic field (EMF)solvers to investigate the printing behavior of EUV multilayer defects. A compression model is applied to compute the defect induced deformation of the multilayer. A fully rigorous Waveguide method is used to simulate the light diffraction from the defective EUV mask. This fully rigorous method is compared with two other methods: A decomposition method combined with the Waveguide algorithm and a hybrid method which computes the multilayer with an analytical method based on the Fresnel-formulas and the mask absorber with a finite-difference time-domain (FDTD) algorithm. Cross sections and the critical dimensions (CD) of the printed wafer features are evaltuated by the application of a threshold model to the computed aerial images. The p rintability of the multilayer defects and their impact on the CD of printed absorber features are investigated versus the defect position, size and other parameters of the defect modell. Finally, the influence of the mask absorber properties on the defect-induced CD variation is investigated. It is shown that the printability of the defect depends on the absorber properties

    Simulation of 3D inclined/rotated UV lithography and its application to microneedles

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    A 3D model is set up to simulate the exposure process of inclined/rotated UV lithography for negative SU-8 resists. The formation of inclined resist pillars and microstructures with truncated cone shapes is simulated based on a 3D exposure model in combination with a post exposure bake model for chemically amplified resists and the Mack development model. As one of the interesting applications employing this promising lithography technique for MEMS fabrication, a solid microneedle for drug delivery is simulated
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