2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/15717A random-matrix theory is presented for the linewidth of a laser cavity in which the radiation is scattered chaotically. The linewidth is enhanced above the Schawlow-Townes value by the Petermann factor K, due to the non-orthogonality of the cavity modes. The factor K is expressed in terms of a non-Hermitian random matrix and its distribution is calculated exactly for the case that the cavity is coupled to the outside via a small opening. The average of K is found to depend non-analytically on the area of the opening, and to greatly exceed the most probable value.4 pages, 2 figures; corrected an error in Fig. 1Chaotic DynamicsMesoscale and Nanoscale PhysicsQuantum Physicstext