Excitation efficiency of a morphology-dependent resonance by a focused Gaussian beam

The excitation efficiency of a morphology-dependent resonance (MDR) by an i ncident beam is defined as the fraction of the beam power channeled into th e MDR. The efficiency is calculated for a focused Gaussian beam of arbitrar y width incident on either a spherical particle or a cylindrical fiber loca ted at an arbitrary position in the plane of the beam waist. In each case a simple formula for the efficiency is derived by use of the localized appro ximation for the beam-shape coefficients in the partial-wave expansion of t he beam. The physical interpretation of the efficiency formulas is also dis cussed. (C) 1998 Optical Society of America [S0740-3232(98)01512-9].