I. Introduction
Vertical-Cavity surface-emitting lasers (VCSELs) are promising candidates in many applications [1]–[9], because of their unique features such as low-power consumption, wafer-level testing for low-cost manufacturing, large-scale 2-D array, high-speed modulation with low driving current, and so on [1]. It is known that VCSELs preferentially emit linear polarized (LP) light along one of the two orthogonal directions (x and y) that coincide with the crystal axes owing to weak material and cavity anisotropies, and can be easily switched between the two orthogonal LP states by modifying the bias current or the device temperature or by applying additional degrees of freedom. The understanding and control of the polarization properties in VCSELs are of fundamental importance in the polarization-sensitive application. Also, the realization of controllable polarization switching (PS) is useful to implement reconfigurable optical interconnects [2], all-optical signal processing for future photonic networks such as optical buffer memory [3]–[5], optical inverter for all-optical regeneration [6]–[8], and all-optical format conversion [9].