Single-mode chirped high-contrast metastructure VCSEL for 106 Gbps PAM4 transmission

Abstract

Short-reach optical interconnects, employing an 850 nm wavelength multimode vertical cavity surface emitting laser (VCSEL) and multimode fiber (MMF), are confronted with transmission distance limitation as the transmission speed increases. Achieving higher speeds over the same transmission distance necessitates a significant enhancement in the fiber’s effective bandwidth, resulting in substantial costs. Employing single-mode VCSEL with single-mode fiber transmission presents as a more economically viable solution. Here we report, to our knowledge, the first demonstration of an 850 nm single-mode VCSEL using a chirped high-contrast metastructure (HCM) as the top mirror with spatially graded reflectivity to suppress higher-order modes. The chirped HCM top reflector is designed to favor lasing of the fundamental mode. We show stable single-mode lasing with a >40dB side mode suppression ratio (SMSR) up to 15 times threshold current and an open eye through a short single-mode fiber SM800 transmission at 106 Gbps PAM4 modulation. This study highlights the potential for scalable single-mode VCSEL in advanced optical interconnects, providing a cost-effective pathway for high-speed applications.