Polarization Switching in Vertical-Cavity Surface-Emitting Lasers With Anisotropic Cavity Geometry and Injection

Vertical-cavity surface-emitting lasers with anisotropic cavity geometry and current injection capable of bias-dependent polarization switching are demonstrated. A cruciform-shaped photonic crystal defect and ion-implanted aperture defines the transverse cavity which is combined with perpendicularly positioned metal contacts for orthogonal electron injection paths. The dominant polarization is determined by the direction of current injection rather than the crystallographic axes as found in isotropic cavities. In addition to polarization control and switching, this type of laser has potential for a novel digital modulation scheme with low-operating-power and high-extinction ratio. The authors achieve 9-dB switching contrast with switching amplitude, with the modulation speed thermally limited.