Ici vous trouverez les présentations issues des Conférences COMSOL à travers le monde. Réalisées par des utilisateurs de COMSOL Multiphysics, ces présentations explorent tous les domaines actuels d'innovation. Les applications couvrent pratiquement tous les secteurs industriels et impliquent des phénomènes électriques, mécaniques, fluidiques et chimiques. Utilisez la recherche rapide pour trouver les présentations les plus intéressantes dans votre domaine d'intérêt.

Modelling Ultra-short Pulse Laser Ablation of Dielectric Materials Using multiple Rate Equations - new

P. Boerner[1], K. Wegener[1]
[1]Institute of Machine Tools and Manufacturing, ETH Zurich, Zurich, Switzerland

Ultrafast lasers are widely applied in micromachining, material science and physics. In industry, picosecond lasers are becoming more and more established. For pulse lengths shorter than the electron-phonon coupling time, heat affected zones are negligible. Thermally sensitive materials can be processed using ultrashort pulse laser radiation. Multi-component materials and poorly absorbing ...

Design and Characterization of MOEMS Optical Tweezers

J. A. Andrews[1], R. Chaubey[1], G. Dwivedi[1], V. Dwivedi[1], N. Sagar[1]
[1]National MEMS Design Center, Department of Applied Physics, Shri G S Institute of Technology & Science, Indore, Madhya Pradesh, India

Optical tweezers work on the idea of non-contact Optical Pressure felt by transparent particles, when shined by coherent light source such as lasers. On the other hand when light falls on the metal it excites the electron inside it and make them free. When these free electron cloud moving in an harmonic frequency it satisfies the resonance condition called surface plasmon resonance (SPR). We ...

Coupling Picosecond Terahertz Pulses to a Scanning Tunneling Microscope

P. H. Nguyen [1], C. Rathje [2], G. J. Hornig [1], V. Jelic [1], C. Ropers [2], F. A. Hegmann [1],
[1] University of Alberta, Edmonton, AB, Canada
[2] 4th Physical Institute, University of Göttingen, Göttingen, Germany

Probing ultrafast processes over subpicosecond and picosecond time scales provides fundamental insight into the nature of materials. We have experimentally demonstrated terahertz (THz)-pulse-induced tunneling in a scanning tunneling microscope (THz-STM) to image surfaces with simultaneous nanometer spatial resolution and subpicosecond time resolution [1]. However, the exact mechanism by which ...

Optical Trapping on Waveguides

O.G. Hellesø [1],
[1] University of Tromsø, Tromsø, Norway

On the surface of an optical waveguide, there is an evanescent field. The evanescent field decays fast and this steep gradient can be used to pull nano- and microparticles down towards the waveguide surface. Radiation forces will propel the particle forward along the waveguide. Trapping on an optical waveguide can be used to manipulate particles in a lab-on-a-chip system where optical methods ...

Dispersion Compensated Optical Fibers for Long Haul Communication

S. C. Hegde [1], S. Agrawal [1], A. Sangeetha [1],
[1] VIT University, Vellore, India

This work highlights the use of COMSOL Multiphysics software for simulating the fundamental electromagnetic mode in a single mode optical fiber, and analyze the effect of refractive index profile , on the overall dispersion of a launched signal . For long haul communication, it is of utmost importance to minimize dispersion in optical fibers, and hence by suitably tailoring the refractive index ...

Design of a Simple and Robust Asymmetric Ellipsometer for Terahertz

G. Rana [1], S. P. Duttagupta [1], P. Deshmukh [2], S. S. Prabhu [2],
[1] Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
[2] Tata Institute of Fundamental Research, Mumbai, Maharashtra, India

Ellipsometry has been the most efficient and accurate method for determining optical constants of a given material. In this article, we present a novel concept for designing an ellipsometer for Terahertz frequencies based on reflection geometry THz Time Domain Spectroscopy. The present ellipsometers for THz are either based on parabolic mirrors cavities or lens based cavities. The former one has ...

TM Wave Propagation in Optical Nanostructures with a Third-Order Nonlinear Response: Modeling and Validation with COMSOL

A. Kildishev[1], E. E. Narimanov[1]
[1]Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, USA

An enhanced method is used for analysis of third-order nonlinearities in optical nanostructures with scalar TM (H-field) frequency domain formulation. After embedding it in COMSOL Multiphysics it is shown to produce fast and accurate results without superfluous vector E-field formalism. A standard TM representation based on cubic non-linear susceptibility χ(3) results in an intractable ...

FE Modeling of Surfaces with Realistic 3D Roughness: Roughness Effects in Optics of Plasmonic Nanoantennas

J. Borneman[1], A. Kildishev[1], K. Chen[1], and V. Drachev[1]

[1]School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA

COMSOL Multiphysics has been widely used to model the near and far-field electromagnetics (specifically, transmission and reflection spectra) of gold and silver nanoantenna arrays. We use a moving 3D mesh, thus preserving the DOF number and simply morphing the structure of the mesh to accommodate the moving boundary. The electromagnetics model consist of four multiphysics models, two ...

Optimal Design for the Grating Coupler of Surface Plasmons

Y. Huang

Mathematics Department, University of California, Los Angeles, CA, USA

We present an optimization procedure to optimize the maximum coupling of free space optical wave to surface plasmon. Shape derivative from shape sensitivity analysis is calculated, and the corresponding partial derivatives of the objective functional with respect to finite number of design variables are derived. An optimal design of the gratings to couple maximum amount of free space photon ...

Simulation of Fourth-Order Laterally-Coupled Gratings

R. Millett, A. Benhsaien, K. Hinzer, T. Hall, and H. Schriemer
Centre for Research in Photonics, University of Ottawa, Ottawa, ON, Canada

Distributed feedback lasers improve the performance of standard Fabry-Perot laser designs by including a wavelength-selective grating that provides superior output, spectral purity and temperature stability. Laterally-coupled distributed feedback (LC-DFB) lasers with the use of higher order gratings have a grating that has been patterned out of the waveguide ridge which allows for simplified ...