Investigation of polarization behavior in a vertical coupled-cavities surface-emitting laser
We report a novel three-contact coupled-vertical-cavity surface-emitting laser (VCSEL) for use in polarization-sensitive optical applications. The device consists in two vertical cavities, coupled by a common semitransparent mirror. We demonstrate that one can independently choose both the power of the output beam - through the current in the first cavity - and the polarization state - through the bias applied to the second cavity. The control of the polarization state is performed with a control of voltage required in the range -2V to 0V. Within this interval the structure exhibits a bistable behavior with respect to the bottom cavity bias. Several physical mechanisms to explain the polarization switch are discussed.