VCSELs: toward higher efficiency and stability

We summarize some of the recent advances in vertical-cavity surface-emitting lasers (VCSELs), primarily focusing on attempting to understand the inherent limitations and advantages of the VCSEL structure in the various wavelength regimes. It will be shown that VCSELs in the 0.8-1.0 μm range should be expected to exceed the performance of their in-plane counterparts in most respects. Reasons include the availability of nearly twice the modal gain for a given cavity fill-factor, the availability of low-loss epitaxial mirrors, the relatively small volume of the active region, and the low numerical aperture of the output beam. Low-resistance electrical pumping schemes have also recently been proven. Wall-plug efficiencies are already higher than in plane in the low-power (⩽1 mW) range, where many optical interconnect applications exist