High-order azimuthal modes in the open resonator

It is proposed that the linearly polarized TEM(0l) azimuthal modes from conventional beam wave theory should be replaced by two other sets of azimuthal modes with different polarization configurations. A theoretical calculation based on complex source-point methods is conducted and the predicted resonant frequencies are compared with those obtained experimentally. It is shown that two series of high-order azimuthal modes should be introduced to replace the conventional linearly polarized TEM(01) modes in a spherical open resonator. It is determined that there is a difference in the resonant frequency between these two series of the same high order l, therefore, these two series cannot be simply added (or subtracted) in order to produce the linearly polarized azimuthal modes.