Abstract

In an important 1979 paper,¹ Petermann pointed out that, in certain laser resonator geometries, a typical mode may exhibit more noise than expected on the basis of the standard quantum mechanical "one photon per mode" prescription. It was subsequently shown by other authors² that this arises because the self-producing field patterns that are commonly referred to as laser "modes" are not true modes of the radiation field. Rather than obeying the familiar condition of power-orthogonality, these satisfy the more general condition of biorthogonality with respect to a set of adjoint modes that correspond to the self-reproducing patterns travelling in the opposite direction.³

© 1994 IEEE