Vertical-Cavity Surface-Emitting Lasers with monolithically integrated Metasurfaces

Doctoral thesis, 2026

The vertical-cavity surface-emitting laser (VCSEL) is a ubiquitous optoelectronic device, driving short-reach communication in data centers and facial recognition. Its claim to fame is its small microcavity, which enables low threshold currents, lasing within a single longitudinal mode, and excellent high-speed modulation. However, the small cavity size implies a significant beam divergence, which means that the VCSEL is typically butt-coupled to a fiber or packaged with bulky external optics. The latest paradigm of miniaturized beam-shaping optics is called metasurfaces, nanostructures with a thickness on the wavelength of light, capable of imparting arbitrary phase and polarization states to an incident beam. By integrating a metasurface directly in the substrate of the VCSEL, its compactness is preserved, eliminating bulky optics and delivering an on-chip, tailored beam.

In this thesis, we present the design and fabrication of a single-mode, single-polarization, bottom-emitting VCSEL monolithically integrated with GaAs metasurfaces, and utilized for miniaturized biophotonic illumination modules. We demonstrate an unconventional metasurface design that circumvents the inherent aspect-ratio-dependent etching limits of monolithic integration, which shapes the light from the VCSEL at very steep angles (>60°) with an exceptional efficiency (>90%). Ultimately, the integrated VCSELs enable a combined dark-field and total internal reflection microscope module, as well as a surface-plasmon resonance sensor that achieves close to state-of-the-art sensitivity, in a miniaturized, flat and an integrated chip format.