STRAIN-INDUCED BIREFRINGENCE IN VERTICAL-CAVITY SEMICONDUCTOR-LASERS

We describe a new technique to study and control the polarization prop erties of planar vertical-cavity semiconductor lasers, The technique c onsists of the application of a controllable amount of strain by means of the thermal expansion that results from local heating in the vicin ity of the device, Analytical expressions are derived for the strain a nd birefringence induced with this hot-spot technique, Experimentally, the relation between strain and birefringence is found to be highly a nisotropic; this allows a natural interpretation of the distribution o f the native polarization angles.