arXiv subjects

L. Deych

Publications and source records attributed to L. Deych.

5 recordsLinked to original sources

arXiv2015

Theory of the nanoparticle-induced frequency shifts of whispering-gallery-mode resonances in spheroidal optical resonators

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.

physics.optics↗

arXiv2011

On optical forces in spherical whispering gallery mode resonators

In this paper we discuss the force exerted by the field of an optical cavity on a polarizable dipole. We show that the modification of the cavity modes due to interaction with the dipole significantly alters the properties of the force. In particular, all components of the force are found to be non-conservative, and cannot, therefore, be derived from a potential energy. We also suggest a simple generalization of the standard formulas for the optical force on the dipole, which reproduces the results of calculations based on the Maxwell stress tensor.

physics.optics↗

arXiv2008

Rayleigh Scattering of Whispering Gallery Modes of Microspheres due to a Single Scatterer: Myths and Reality

The interaction of whispering gallery modes (WGM) of optical microresonators with subwavelength imperfections has been studied both experimentally and theoretically. This interaction is responsible for the formation of spectral doublets in place of single resonance peaks, and for degrading of Q-factors of the resonances. Within the currently accepted framework the spectral doublets are explained as a result of degeneracy removal of clockwise and counterclockwise WGMs due to their coupling caused by defect-induced backscattering, while the degrading of the Q-factor is described phenomenologically as an additional contribution to the overall decay rate of WGM due to coupling between WGM and radiative modes. Here we show that the existing understanding of this phenomenon is conceptually wrong and develop an exact theory of WGM interaction with a single defect, which provides a unified treatment for both aspects of this interaction explaining existing experiments and predicting new phenomena.

physics.optics↗

arXiv2005

Photonic band mixing in linear chains of optically coupled micro-spheres

The paper deals with optical excitations arising in a one-dimensional chain of identical spheres due optical coupling of whispering gallery modes (WGM). The band structure of these excitations depends significantly on the inter-mixing between WGMs characterized by different values of angular quantum number, $l$. We develop a general theory of the photonic band structure of these excitations taking these effects into account and applied it to several cases of recent experimental interest. In the case of bands originating from WQMs with the angular quantum number of the same parity, the calculated dispersion laws are in good qualitative agreement with recent experiment results. Bands resulting from hybridization of excitations resulting from whispering gallery modes with different parity of $l$ exhibits anomalous dispersion properties characterized by a gap in the allowed values of \emph{wave numbers} and divergence of group velocity.

physics.optics↗

arXiv2003

Comment on: "Mode repulsion and mode coupling in random lasers" by Cao et al. Phys. Rev. B {\bf 67}, 161101 (R) (2003)

In recent paper Cao et al. [Phys. Rev. B {\bf 67}, 161101 (R) (2003)] reported an observation of what is the first genuine multi-mode behavior in random lasers. They observed a splitting of a single lasing line into two lines with close frequencies when pumping is increased beyond a certain threshold. Here we are pointing out that the qualitative interpretation of these experiments given in that paper is misleading.

cond-mat.dis-nn↗