Efficient Tunnel Junction Lithographic Aperture 940 nm VCSEL

We report on oxide free 940 nm VCSELs based on a buried tunnel junction acting as a lithographic aperture and achieving power conversion efficiency above 40%. We present the fabrication flow implementing a 2-step epitaxial growth as well as a detailed electro-optical characterization of the fabricated devices. The tunnel junction based VCSELs benefit from a uniform current distribution thanks to a low resistive n-doped top DBR. The mesa-free lithographically defined aperture enables the arrangement of compact arrays constituted of small single mode emitters. Such array configuration allows to scale up the generated optical power while maintaining a diffraction-limited Gaussian beam and limiting the impact of thermal rollover.