Using quasiclassical approach rather precise analytical approximations for the eigenfrequencies of whispering
gallery modes in convex axisymmetric bodies may be found. We use the eikonal method to analyze the limits
of precision of this approach using as a practical example spheroidal dielectric cavity. The series obtained for
the calculation of eigenfrequency is compared with the known series for dielectric sphere and numerical
Quasiclassical approach and geometric optics allow to describe rather
accurately whispering gallery modes in convex axisymmetric bodies. Using this approach we obtain practical formulas for the calculation of eigenfrequencies and radiative Q-factors in dielectrical spheroid and compare them with the known solutions for the particular cases and with numerical calculations. We show how geometrical interpretation allows expansion of the method on arbitrary shaped axisymmetric bodies.
Properties of whispering gallery modes in microresonators of different types proposed lately may be analyzed with the help of introducing equivalent spheroid. We describe and compare two methods of approximate calculation of scalar field equation in such spheroid.
Thermal nonlinearity can produce oscillatory instability in
optical microspheres. We analyze theoretically the conditions of
observations of this regime and demonstrate it experimentally. The
observed curves are well compared with results of numerical
modelling. In pure fused silica with low absorption thermal
oscillations are suppressed due to concurrency with Kerr
nonlinearity. We also describe for the first time experimentally
observed slow and irreversible thermooptical processes in