Relative intensity noise of vertical-cavity surface-emitting lasers subject to variable polarization-optical feedback

In this paper, the influence of variable polarization angle of the optical feedback on the relative intensity noise (RIN) of a vertical-cavity surface-emitting laser (VCSEL) is experimentally investigated. VCSEL lases in two orthogonally polarized (XP and YP) modes. For the dominant polarization mode (i.e. XP) the RIN is minimum at a polarization angle of 0°, while it is a minimum at 90° for the suppressed polarization mode (YP) it is minimum at a polarization angle of 90°. Furthermore, for a high optical feedback level the RIN of the XP mode increases rapidly with the polarization angle, whereas for the YP mode the RIN is low for angles > 45°. In addition, result shows that the relaxation oscillations are damped due to the optical feedback. We also show that as the polarization angle of the optical feedback increases a number of spectral lines appear in VCSEL spectrum, thus representing the complex dynamics behavior induced by the feedback.