Abstract

We present analytical and numerical results indicating pattern formation in a purely absorptive medium, namely a resonantly-excited two-level system in a ring cavity. Pattern formation occurs when the cavity is mistuned such that the optical wavelength exceeds that of the nearby cavity mode. But then off-axis or "tilted" waves can exactly fit the cavity, and this determines the dominant transverse wave vector of the pattern. This is a geometrical, linear, and very general mechanism found also in lasers¹ and recently in OPOs.²

© 1994 IEEE