Investigation of the mode splitting induced by electro-optic birefringence in a vertical-cavity surface-emitting laser by polarized electroluminescence

The mode splitting induced by electro-optic birefringence in a P–I–N InGaAs/GaAs/AlGaAs vertical-cavity surface-emitting laser (VCSEL) has been studied by polarized electroluminescence (EL) at room temperature. The polarized EL spectra with E‖110 and E‖110 directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence. This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.