In: Current Nanoscience, 2006, vol. 2, no. 4, p. 337350
High Resolution Interference Microscopy (HRIM) is a technique that allows the characterization of amplitude and phase of electromagnetic wavefields in the farfield with a spatial accuracy that corresponds to a few nanometers in the object plane. Emphasis is put on the precise determination of topological features in the wavefield, called phase singularities or vortices, which are spatial...

In: Optics Letters, 2004, vol. 29, no. 18, p. 21812183
We use rigorous diffraction theory to analyze the force on elliptical cylinders made from silver as a function of the elongation. We find that, when the wires are illuminated at the plasmon wavelength and placed in a highly focused Gaussian beam, they are attracted toward the optical axis if the waist of the laser is behind the wire and repelled if the waist is before the wire. Also, the force...

In: Journal of the Optical Society of America A, 2003, vol. 20, no. 10, p. 19691973
The boundaryelement 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 nearfield amplitude and a large scattering cross section. The resonance wavelength for different scatterer geometries is determined. Alteration of the scattering properties in the...

In: Journal of the Optical Society of America A, 2005, vol. 22, no. 1, p. 109116
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 sizedependent 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...

In: Journal of the Optical Society of America B, 2005, vol. 22, no. 2, p. 481487
We investigate the smallparticle phononpolariton 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...

In: Journal of the Optical Society of America A, 2004, vol. 21, no. 9, p. 17611768
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...

In: Journal of Optics A: Pure and Applied Optics, 2004, vol. 6, no. 5, p. 271276
Phase singularities appear in the diffracted farfield of an optical microstructure 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 farfield. Using scalar theory, an analytical equality is derived that must be met by the structure. Because...

In: Journal of Optics A: Pure and Applied Optics, 2004, vol. 6, no. 10, p. 921931
Illumination of nano and microparticles 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...

In: Optics Communications, 2004, vol. 235, no. 13, p. 1121
In the present paper, we determine the conditions necessary for the generation of phase singularities in the farfield 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....

In: Optics Communications, 2004, vol. 242, no. 13, p. 163169
We present measurements of the intensity as well as the phase distribution in the various diffraction orders of computergenerated holograms designed to generate a higher order Gauss–Laguerre beam. For the direct measurement of the phase distribution in the diffraction orders a highresolution interferometer is used, which allows access to a lateral length scale for the localization of phase...
