Efficient scaling of VCSELs to wavelength dimensions via lithographically defined cavities

Abstract The miniaturization of lasers is critical for on-chip optical communication and high-speed data processing beyond the limits of electronics and current high-speed lasers. Vertical-cavity surface-emitting lasers (VCSELs) are the leading technology due to their compact size, low power consumption, and high-speed modulation capabilities. However, achieving broader modulation bandwidth and more energy-efficient transmission requires scaling to near- and sub-wavelength dimensions, presenting challenges for conventional VCSELs. Here, we introduce a lithographic approach utilizing an intracavity phase-shifting mesa that can provide transverse photonic and electrical confinement, reducing optical losses and enhancing scalability. We demonstrate lithographically defined VCSELs with high quality factors, supporting wavelength-scale devices with diameters ranging from 0.75 to 2.0 µ m. These devices achieve continuous-wave operation at room temperature with single-mode emission and high efficiency. Furthermore, the resonance wavelength can be tuned via a wavelength-tuning layer, enhancing spectral flexibility. Our experimental results align well with numerical analysis, representing a significant step toward ultra-compact, electrically pumped lasers for next-generation photonic technologies, including data center interconnects and quantum photonic applications.