High-speed VCSEL arrays enabled by monolithic high-index-contrast gratings

Vertical-cavity surface-emitting lasers (VCSELs) are key enabling components in high-speed data communication, sensing, and integrated photonics. However, combining high modulation bandwidth, stable single-mode emission, and power efficiency in a compact and manufacturable design remains a challenge. We demonstrate that replacing the conventional p-side distributed Bragg reflector (DBR) with a monolithic high-index-contrast grating (MHCG) enables a new class of high-performance VCSELs with scalable and tunable optical properties. Using this approach, we achieve modulation bandwidths up to 30 GHz, matching dual-DBR reference devices, confirming that the MHCG maintains high modulation speed. The highest bandwidths were achieved with oxide apertures up to 7 µm, ensuring a low current density, which is beneficial for extending device lifetime. The MHCG provides strong polarization and mode selectivity, resulting in linearly polarized single-mode emission with a side-mode suppression ratio of >40dB across the entire operating current range. Additionally, up to 6 nm wavelength tuning was achieved across five adjacent VCSELs by varying the MHCG geometry. We thus establish the MHCG as a powerful tool for engineering next-generation high-speed VCSELs with precise control over emission characteristics for a wide range of application scenarios.