Spectroscopic study of optical confinement and transport effects in coupled microspheres and pillar cavities

In this thesis we investigated the spatial and spectral mode profiles, and the optical transport properties of single and multiple coupled cavities. We performed numerical modeling of whispering gallery modes (WGMs) in such cavities in order to explain recent experiments on semiconductor micropillars. High quality (Q up to 20 000) WGMs with small mode volumes V ∼0.3 mum 3 in 4-5 mum micropillars were reproduced. The WGM spectra were found to be in a good agreement with the experimental data.;The coupling between size-matched spheres from 2.9 to 6.0 mum in diameter was characterized using spectroscopy. We observed peculiar kites in the spectral images of such coherently coupled bispheres. The origin of these kites was explained due to the coupling of multiple pairs of azimuthal modes. We quantified the coupling constant for WGMs located in the equatorial plane of spheres parallel to the substrate which plays the most important role in the transport of WGMs in such structures.;It was shown that in long (>10 spheres) chains of size-disordered polystyrene microspheres the transmission properties are dominated by photonic nanojet-induced modes (NIMs) leading to periodic focusing of light along the chain. In the transmission spectra of such chains we observed Fabry-Perot fringes with propagation losses of only 0.08 dB per sphere at the maxima of the transmission peaks. The fringes of NIMs are found to be in a good agreement with the results of numerical modeling. These modes can be used in various biomedical applications requiring tight focusing of the beams.