In this paper, optical properties of coupled silica disk microresonators are investigated. The spectral response and the light intensity distribution along the coupled disks were measured. It was found that the distribution depends on the particular excited resonance, which can be attributed to the formation of normal modes of the coupled resonator system. A developed theoretical model gives quantitative agreement with the experimental observations

Nanoparticle-induced modifications of the spectrum of whispering-gallery-modes (WGM) of optical spheroidal resonators are studied theoretically. Combining an ab initio solution of a single resonator problem with a dipole approximation for the particle, we derive simple analytical expressions for frequencies and widths of the particle-modified resonances, which are valid for resonators with moderate deviations from the spherical shape. The derived expressions are used to analyze spectral properties of the resonator-particle system as functions of the particle's position, the size of the resonators and the characteristics of WGMs. The obtained results are shown to agree well with available experimental data. It is also demonstrated that the particle-induced spectral effects can be significantly enhanced by careful selection of resonator's size, refractive index and other experimental parameters. The results presented in the paper can be useful for applications of WGM resonators in biosensing, cavity QED, optomechanics and others. PACS 42.25.Bs, 42.25.Fx, 42.60.Da

Statistical properties of a laser based on a one-dimensional disordered superlattice open at one side are studied numerically. The passive normal modes of the system are determined using the Feshbach projection technique. It is found that the mode competition due to the spacial hole burning leads to a saturation of the number of lasing modes with increasing pump rate. It is also responsible for nonmonotonic dependence of intensities of lasing modes as functions of pumping. Computed distributions of spectral spacing and intensity statistics are in qualitative agreement with experimental results.

The recently developed general ab initio theory of nanoparticle-induced modifications of the spectrum of whispering gallery modes of optical spheroidal resonators is applied to the case in which distinct particle-induced resonances overlap and cannot be resolved. This situation occurs in the case of resonances with low Q-factors and/or ultra-small particles. The position of the single resonance observed in these situations depends on the strengths and widths of the overlapping resonances. We determine this position by considering the spectral characteristics of the total power scattered by the resonator. The obtained theoretical results are compared against the available experimental data and heuristic theories.

For submonolayer quantum dot (QD) based photonic devices, size and density of QDs are critical parameters, the probing of which requires indirect methods. We report the determination of lateral size distribution of type-II ZnTe/ZnSe stacked submonolayer QDs, based on spectral analysis of the optical signature of Aharanov-Bohm (AB) excitons, complemented by photoluminescence studies, secondary-ion mass spectroscopy, and numerical calculations. Numerical calculations are employed to determine the AB transition magnetic field as a function of the type-II QD radius. The study of four samples grown with different tellurium fluxes shows that the lateral size of QDs increases by just 50%, even though tellurium concentration increases 25-fold. Detailed spectral analysis of the emission of the AB exciton shows that the QD radii take on only certain values due to vertical correlation and the stacked nature of the QDs.