Tailoring light polarization in vertical cavity surface emitting lasers by isotropic optical feedback from an extremely short external cavity

Abstract

The authors experimentally show that isotropic optical feedback from an extremely short external cavity can induce switching between the two fundamental transverse modes with orthogonal linear polarization of otherwise (without optical feedback) polarization stable vertical cavity surface emitting laser. The switching currents and the hysteresis width can be widely tuned by varying the external cavity length. Moreover, by a proper choice of the optical feedback parameters, the emission can be stabilized in any of the two linearly polarized modes.

Polarization control of 1.6 μm vertical-cavity surface-emitting lasers using InAs quantum dashes on InP(001)

“…For example VCSELs based on noncylindrical cavities, on spatial gain or loss anisotropy, on the use of external stress or optical feedback have been successfully realized. 5,[9][10][11] They show a polarization control toward a specific direction, with an orthogonal polarization suppression ratio ͑OPSR͒ being for the best value close to 30 dB. Nevertheless, most of these realizations increase the fabrication complexity and cost.…”

“…[5][6][7][9][10][11] We believe that the fixed polarization and such an important and stable OPSR are mainly due to the QDH in-plane optical anisotropy. Ukhanov et al 20 have reported a QDH TE gain ratio close to 2 in linear SOA, depending of the QDH alignment ͑parallel or perpendicular͒ in reference to the SOA cavity axis.…”