Generalised open resonator theory

The complex-source-point technique has the merit of providing exact field expressions of higher-order Laguerre-Gaussian beam modes. These field expressions are used to derive resonant frequencies, with known order of accuracy, of a spherical open resonator with unequal mirrors. The result is not only more accurate than the conventional resonant formula, but also provides the order of accuracy for it. Moreover, the nondegeneracy between the EHl¿¿1, p + 1 and HEl + 1, p + 1 beam modes is also confirmed.