In this paper comprehensive experimental research on high-power semiconductor lasers that possess a non-zero TM-mode power (typically few percent of the total power) and elliptical polarization in solitary configuration in the vicinity of critical angle is described. Critical angle is obtained when the TE(TM)-mode mean power reaches its minimum (maximum). The elliptical polarization of the laser at critical angle is determined through measurement of the Stokes parameters. When subject to a self-feedback with variably rotated polarization interesting effects are identified, such as dynamical collapses which address selectively the TM-mode of the laser and the appearance of a significant splitting in the optical spectrum (typically few nm).