Results are presented of theoretical and experimental investigations of whispering-gallery oscillations in a shielded isotropic layered spherical dielectric cavity. Oscillations whose Q factor is two orders of magnitude higher than that of the oscillations of an open dielectric sphere are studied. Intermode interaction is observed between various cavity oscillation modes.

High-Q whispering-gallery oscillations in a shielded spherical dielectric cavity

Resonant oscillations of homogeneous isotropic dielectric ball was investigated analytically and numerically [I]. It \ms shown that at big polar index n whispering gallery modes (WGM's) are excited in it. The special peculiarity of these modes is electromagnetic field concentration along the ball interface. It is known that WGM's have high Q-factor. At the first time they were observed in stimulated radiation of a spherical pattern, later in nuclear cavitation experiments , Wan light scattering in aierosols, and in ruby ball and so on (24. High Q-factor , discovering the areas of the field localization of the resonant modes allowed to suggest set of devices with new unique properties, to calculate quite small losses in crystals and liquids [2-5].

Whispering Gallery Oscillations In An Anisotropy Ball

The anisotropy of parameters is an intrinsic characteristic feature of dielectrics employed in production of high-Q resonators. A theory of azimuthal-homogeneous resonant oscillations in a single-crystal sphere is developed. It is demonstrated that the anisotropy gives rise to TM oscillations of two orders at different frequencies. Oscillations with large polar indices are numerically investigated.

Resonant Frequencies of Azimuthal-Homogeneous Oscillations of an Anisotropic Sphere

The implementation of spherical geodesic processors without any conventional waveguide is considered. The guided propagation is assured by the whispering gallery modes due to the curvature. The electric field distributions of these modes are given in the approximation of small bending losses, that is when the sphere radius rho >> lambda (in practice rho =1-20 mm). The dispersion equation of the modes and the attenuation due to the path curvature were also found. Experiments were carried out on a BK7 glass quarter of sphere ( rho =15 mm) at lambda =0.63 mu m and on a GaAs hemisphere ( rho =9.2 mm) at lambda =1.31 mu m.

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Papers

Whispering propagation at optical frequencies for spherical geodesic processors