CORRELATION BETWEEN POLARIZATION AND INTENSITY IN ARGON-ION LASERS

The nature and behavior of the eigenstates of a multimode argon-ion la ser containing a variable linear loss anisotropy and submitted to a lo ngitudinal magnetic field are theoretically and experimentally investi gated. In particular it is shown that for a given value of the loss an isotropy a transition occurs for a given value of the longitudinal mag netic field. This defines the concept of a critical magnetic field for multimode lasers. For this value of the magnetic field the eigenstate s of the multimode laser pass from linearly polarized eigenstates to c ircularly polarized eigenstates. The shapes of the output spectra for the different behaviors are discussed and observed, and the correlatio n between the nature of these eigenstates and the output power of the laser is investigated. The puzzling output power enhancement caused by the insertion of a Brewster window is interpreted.