Reciprocal transmissions and asymmetric modal distributions in waveguide-coupled spiral-shaped microdisk resonators

Abstract

In a recent article [Opt. Express 15, 14650 (2007)] Lee et al. claimed that optical modes in spiral-shaped microcavities come in pairs of clockwise and counterclockwise traveling-wave modes having the same frequencies and Q-factors but different modal distributions. In this comment, we show that the opposite is true: the modes are in general nondegenerate in terms of frequencies and Q-factors and the modal distributions are similar.