Université de Neuchâtel

Application of the boundary-element method to the interaction of light with single and coupled metallic nanoparticles

Rockstuhl, Carsten ; Salt, Martin Guy ; Herzig, Hans-Peter

In: Journal of the Optical Society of America A, 2003, vol. 20, no. 10, p. 1969-1973

The boundary-element method is applied to the interaction of light with resonant metallic nanoparticles. At a certain wavelength, excitation of a surface plasmon takes place, which leads to a resonantly enhanced near-field amplitude and a large scattering cross section. The resonance wavelength for different scatterer geometries is determined. Alteration of the scattering properties in the...

Université de Neuchâtel

Calculation of the torque on dielectric elliptical cylinders

Rockstuhl, Carsten ; Herzig, Hans-Peter

In: Journal of the Optical Society of America A, 2005, vol. 22, no. 1, p. 109-116

We present our investigation of the torque exerted on dielectric elliptical cylinders by highly focused laser beams. The calculations are performed with rigorous diffraction theory, and the size-dependent torque is analyzed as a function of the axis ratio. It is found that highly elongated particles will experience a reversal of the torque for a radius that is approximately one third of the...

Université de Neuchâtel

Analysis of the phonon-polariton response of silicon carbide microparticles and nanoparticles by use of the boundary element method

Rockstuhl, Carsten ; Salt, Martin Guy ; Herzig, Hans-Peter

In: Journal of the Optical Society of America B, 2005, vol. 22, no. 2, p. 481-487

We investigate the small-particle phonon-polariton response of several microstructures that are made of silicon carbide (SiC). Phonon polaritons can be excited in a wavelength region between 10 and 12 µm. Simple structures such as elliptical cylinders support phonon polaritons at two wavelengths, which depend on the axis ratio of the particle. In particles with a more irregular shape such as...

Université de Neuchâtel

Analyzing the scattering properties of coupled metallic nanoparticles

Rockstuhl, Carsten ; Salt, Martin Guy ; Herzig, Hans-Peter

In: Journal of the Optical Society of America A, 2004, vol. 21, no. 9, p. 1761-1768

We apply the boundary element method to the analysis of the plasmon response of systems that consist of coupled metallic nanoscatterers. For systems made of two or more objects, the response depends strongly on the individual particle behavior as well as on the separation distance and on the configuration of the particles relative to the illumination direction. By analyzing the behavior of these...

Université de Neuchâtel

Theoretical and experimental investigation of phase singularities generated by optical micro- and nano-structures

Rockstuhl, Carsten ; Salt, Martin Guy ; Herzig, Hans-Peter

In: Journal of Optics A: Pure and Applied Optics, 2004, vol. 6, no. 5, p. 271-276

Phase singularities appear in the diffracted far-field of an optical micro-structure if the object is of a sufficient lateral size to induce an appropriate phase delay. We present results that determine the critical dimension of a single phase bar for the generation of dislocations in the far-field. Using scalar theory, an analytical equality is derived that must be met by the structure. Because...

Université de Neuchâtel

Rigorous diffraction theory applied to the analysis of the optical force on elliptical nano- and micro-cylinders

Rockstuhl, Carsten ; Herzig, Hans-Peter

In: Journal of Optics A: Pure and Applied Optics, 2004, vol. 6, no. 10, p. 921-931

Illumination of nano- and micro-particles with a highly focused laser beam will exert a force on them that depends on different parameters, such as the particle size, refractive index and beam waist. In this paper rigorous diffraction theories are used to calculate the force on elliptically shaped dielectric cylinders in three different size regimes. We analyse the conditions for which the...

Université de Neuchâtel

Investigation of the basic properties of phase singularities generated by a phase bar or trench

Rockstuhl, Carsten ; Salt, Martin Guy ; Herzig, Hans-Peter

In: Optics Communications, 2004, vol. 235, no. 1-3, p. 11-21

In the present paper, we determine the conditions necessary for the generation of phase singularities in the far-field by a phase bar or a trench. The ultimate goal of our work is to link object parameters to a topological distribution of pairs of singularities. We apply scalar theory and show that objects smaller than the diffraction limit are not capable of generating singularities....

Université de Neuchâtel

High-resolution measurement of phase singularities produced by computer-generated holograms

Rockstuhl, Carsten ; Ivanovskyy, Andrey Albert ; Soskin, Marat Samuil ; Salt, Martin Guy ; Herzig, Hans-Peter ; Dändliker, René

In: Optics Communications, 2004, vol. 242, no. 1-3, p. 163-169

We present measurements of the intensity as well as the phase distribution in the various diffraction orders of computer-generated holograms designed to generate a higher order Gauss–Laguerre beam. For the direct measurement of the phase distribution in the diffraction orders a high-resolution interferometer is used, which allows access to a lateral length scale for the localization of phase...

Université de Neuchâtel

Infrared Gratings Based on SiC/Si-heterostructures

Rockstuhl, Carsten ; Herzig, Hans-Peter ; Förster, C. ; Leycuras, A. ; Ambacher, O. ; Pezoldt, J.

In: Materials Science Forum (MSF), 2005, vol. 483-485, p. 433-436

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Université de Neuchâtel

Properties of light fields near sub-micro and nano-scale structures

Rockstuhl, Carsten ; Herzig, Hans Peter (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2004 ; 1786.

In this thesis various phenomena that appear if light interacts with objects having a size comparable to the wavelength are experimentally and theoretically analysed. The work is concentrated on the analysis of phase singularities in electromagnetic fields, on the excitation of plasmon-polaritons and phonon-polaritons in arbitrary shaped cylindrical objects and on the analysis of force and torque...