Coupled TE-TM mode dynamics in a semiconductor laser subject to optical feedback: "The underdog's triumph" scenario

We investigate experimentally and theoretically the dynamics of polarization modes in a semiconductor laser subject to optical feedback exclusively into its dominant polarization mode. The laser, despite being edge emitting, weakly supports the orthogonally polarized mode even in a solitary configuration, i.e., without optical feedback. When subject to optical feedback, the laser displays transition behavior from correlated to anticorrelated dynamics between the polarization modes as a function of the injection current strength. We construct a theoretical model based on the Lang-Kobayashi rate equations to describe these results. We include coupling between the two polarization modes in the gain medium to reflect persistence of the second mode in both solitary configuration and under external feedback. With this coupling, the model can reproduce the observed experimental results.