Volume 87, Number 3, August 2009
Article Number 34003
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 27 August 2009
EPL, 87 (2009) 34003
DOI: 10.1209/0295-5075/87/34003

Internal and external resonances of dielectric disks

C. P. Dettmann1, G. V. Morozov1, 2, M. Sieber1 and H. Waalkens1, 3

1   Department of Mathematics, University of Bristol - Bristol BS8 1TW, UK, EU
2   Thin Film Centre, University of the West of Scotland - Paisley PA1 2BE, UK, EU
3   Department of Mathematics, University of Groningen - Nijenborgh 9, 9747 AG Groningen, The Netherlands, EU

received 27 March 2009; accepted in final form 23 July 2009; published August 2009
published online 27 August 2009

Circular microresonators (microdisks) are micron size dielectric disks embedded in a material of lower refractive index. They possess modes with complex eigenvalues (resonances) which are solutions of analytically given transcendental equations. The behavior of such eigenvalues in the small opening limit, i.e. when the refractive index of the cavity goes to infinity, is analyzed. This analysis allows one to clearly distinguish between internal (Feshbach) and external (shape) resonant modes for both TM and TE polarizations. This is especially important for TE polarization for which internal and external resonances can be found in the same region of the complex wave number plane. It is also shown that for both polarizations, the internal as well as external resonances can be classified by well-defined azimuthal and radial modal indices.

42.55.Sa - Microcavity and microdisk lasers.
42.25.-p - Wave optics.
03.50.De - Classical electromagnetism, Maxwell equations.

© EPLA 2009