Use of a generalized method of eigenmodes in the theory of lasers

An analysis is made of the application a generalized method of eigenmodes, which is used in steady-state diffraction problems to the theory of lasers. In the study of open laser cavities the use of this method makes it possible to avoid difficulties associated with the exponential growth of the field at infinity. The generalized method developed previously for solving steady-state diffraction problems is extended to the case of non-steady-state narrow-band processes to construct in the ordinary way the equations describing the operation of the laser. The only difference is that the field is expanded in the eigenfunctions that are orthogonal in the region occupied by the active medium. This eliminates the difficulties associated with the behavior of the mode field at infinity. In addition, in a number of cases the generalized eigenfunctions (modes) correspond considerably better to the field distribution in the operating laser. Zh. Tekh. Fiz. 67, 46–49 (June 1997)