''Semiconductor laser subject to intense feedback with variably rotated polarization''

A semiconductor laser subject to delayed optical feedback is investigated in the limit of intense feedback power. Back-injection of light with variably rotated polarization reveals a symmetry breaking in laser emission spectra and output power when the rotation angle is changed in the vicinity of the orthogonal orientation. To explain the observed asymmetry we propose a simple geometric model which includes the relative contributions of both TE and TM lasing modes into the feedback light. In a range of feedback polarization rotation angles the emission spectra of the laser reveal a gap with width of more than a terahertz. The position of the gap and its width are shown to be regulated by means of feedback polarization rotation angle. We demonstrate that a theoretical approach, based on carrier density grating induced potential, explains our experimental results.