On the antiresonances of a microcavity with quarter-wave dielectric mirrors

The amplitude reflectivity spectrum and the associated finesse of a microcavity with quarter-wave dielectric mirrors have been theoretically analysed. Triangular-shaped antiresonances were obtained when the radius of the incident beam was not much larger than a wavelength. This was due to the dispersion caused by high spatial frequency components of the incident beam. The dispersion resulted in an increase of the width of the high-transmission region, and therefore greatly degraded the finesse of the cavity.