Università Cattolica del Sacro Cuore – Sede di Brescia
Nano-localization of polarized light: characteristics
Dott. Matteo Savoini
Light polarization has been extensively studied since the beginning of 1800s; since then, a lot of different applications have been found dealing with differently polarized states of light, the most known being LCD screens. All these possible different applications have been extensively exploited in a range of dimensions far from the smallest diffraction-limit areas attainable.
With the development of nanotechnology, strong interest has been devoted in the confinement of light beams in order to have higher and higher resolving power, thus the possibility to study light-matter interaction on an extremely small scale. So techniques like conventional optical microscopy nowadays employ objective lens with high focusing power (defined by the numerical aperture), allowing resolutions down to few hundreds nanometer, with visible illumination light. Even better resolution can be attained by less conventional techniques; like scanning near-field microscopy (SNOM), where typically we have resolution of 100 nm. Even further improvement in the resolution can be obtained with plasmonic nanoantennas, where the electric field can be confined to dimensions down to 10/20 nm. Especially in the sub-diffraction limit, little work has been done about the study of light polarization.
With the use of polarization preserving objectives, and/or special near-field probes, we are now able to demonstrate that it is indeed possible to implement polarization sensitive applications and analysis on areas well below 1 μm2. In this way, a huge number of different applications can be envisaged and studied ranging from polymeric science to magnetic/metallic materials