Novel single-transverse-mode control of VCSELs with dielectric mode filter

We establish a novel method of controlling the transverse modes of vertical cavity surface emitting lasers (VCSELs) to achieve 1 mW single-fundamental-mode lasing. A dielectric mode filter is installed on top of the VCSEL. The dielectric layer (SiO2) is deposited and patterned to modify the mirror reflectivity across the oxide aperture via antiphase reflections. This mode selection is nondestructive and universally applicable for other structures under single transverse mode. Destructive etching techniques (dry/wet) or epitaxial regrowth are also not required. This method simplifies the preparation process and improves the repeatability of the device. Measurements show that under continuous-wave current injection, the side-mode suppression ratio exceeds 30 dB.