Beyond 30 mW of Single-Mode Power in Linearly-Polarised VCSELs

We present a set of design rules for high-power single-polarisation-mode (SPM) vertical-cavity surface-emitting lasers (VCSELs) featuring an axial far-field (FF) intensity profile, and validate them through the fabrication and experimental characterization of dedicated prototypes. We employ a surface-patterning technique enabling both the selection of a target higher-order mode and a reshaping of its FF profile, by etching a grating-relief array in the VCSEL cap layer and growing a dielectric rephasing section. After having identified the rectangle and the donut as optimal oxide aperture shapes in terms of thermal dissipation and FF properties, corresponding prototypes are experimentally fabricated and measured, confirming the simulations. For the rectangle, a SPM power of 13 mW is demonstrated; for the donut, a doubled maximum SPM power of 27 mW, both with centered FFs. The presented results pave the way for continuous-wave high-power single-mode axial-emitting VCSELs, exceeding the previously reported SPM power values. 100 mW are then predicted, grounded on the above achievements. This is particularly interesting for quantum sensing and free-space communication and will certainly attract interest in other applications that have not yet addressed VCSELs due to their current too-low SPM power performance.