KEYWORDS: Metals, Near field scanning optical microscopy, Near field, Near field optics, Polarization, Coating, Liquid crystals, Aluminum, Quartz, Radio propagation
Fully-metal-coated near-field optical probes, based on a cantilever design, have been studied theoretically and experimentally. Numerical simulations prove that these structures allow non-zero modal emission of the electromagnetic field trough a 60 nm thick metallic layer, that is opaque when deposited on flat substrates. The far-field intensity patterns recorded experimentally correspond to the ones calculated for the fundamental and first excited LP modes. Moreover, this study demonstrates that a high confinement of the electromagnetic energy can be reached in the near-field, when illuminated with radially polarized light. Finally, it was verified that the confinement of the field depends on the volume of the probe apex. The coupling and transmission of transverse and longitudinal fields into the probes has been also investigated. Two kinds of probes with different metal coating roughness are considered. Transverse and longitudinal field distributions are obtained by focusing azimuthally and radially polarized beams produced by means of a liquid crystal plate. The focal plane is scanned using microfabricated probes in a collection mode configuration. It is found that the roughness of the metal coating plays an important role in the coupling strength of transverse fields into the probes: the relative coupling efficiency for transverse fields diminishes with a rough metal coating, while that of longitudinal fields does not.
KEYWORDS: Near field scanning optical microscopy, Heterodyning, Optical microscopes, Polarization, Near field optics, Phase measurement, Near field, Interferometry, Nd:YAG lasers, Diffraction gratings
A coherent scanning near-field optical microscope (SNOM) is presented. The set-up employs heterodyne interferometry, allowing measurements of both amplitude and phase of the optical field. Experimental results show polarization effects that reveal important information about the vectorial field conversion by the fiber tip.
In view of future generations of biosensors, immobilization of biomolecules with high spatial resolution onto selected materials or transducer surfaces is required. One way to attach the biomolecules is to induce covalent bonds with the substrate using a photochemical effect. High localization in the attachment is obtained when performing the photochemistry in the next field. In this paper, we present patterns of covalently bond proteins, written with near field UV activation. Observation is done in the near field as well, using near field fluorescence microscopy.
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