Polarisation characteristics of quantum well vertical cavity surface emitting lasers

The polarisation properties of quantum well vertical cavity surface emitting lasers are observed to be significantly different from their edge emitting counterparts. A near threshold, highly linearly polarised TEMoo mode whose direction varies randomly from one laser to the other is obtained. At higher currents, high order modes lase in a linear polarisation orthogonal to the fundamental mode. No polarisation selection rule is observed.