Polarization selection and sensitivity of external cavity vertical-cavity surface-emitting laser diodes

A theoretical analysis has been undertaken of the polarization properties of birefringent vertical-cavity surface-emitting lasers (VCSELs) subject to weak optical feedback in an external cavity configuration. Attention is focussed on the competition between two orthogonal polarizations of the fundamental (LP/sub 01/) transverse mode of the device. It is shown that control of the emission polarization can be exercised even for very small external reflectivities (10/sup -4/%) by appropriate choice of optical feedback delays. The polarization selectivity is shown to be dependent upon the strength of optical feedback. Polarization is also shown to be highly sensitive to small changes in optical feedback delay. Thermally induced wavelength shift is shown to affect polarization behaviour.