Geometrical optics model of Mie resonances

The geometrical optics model of Mie resonances is presented. The ray path g eometry is given and the resonance condition is discussed with special emph asis on the phase shift that the rays undergo at the surface of the dielect ric sphere. On the basis of this model, approximate expressions for the pos itions of first-order resonances are given. Formulas for the cavity mode sp acing are rederived in a simple manner. It is shown that the resonance line width can be calculated regarding the cavity losses. Formulas for the mode density of Mie resonances are given that account for the different width of resonances and thus may be adapted to specific experimental situations. (C ) 2000 Optical Society of America [S0740-3232(00)00707-9] OCIS codes: 080.0 080, 290.0290, 080.1510, 290.4020, 140.4780, 260.5740.