MicroVCSELs vs MicroLEDs, a MicroExplainer

Short-reach data center interconnects are transitioning from microLEDs to microVCSELs to address the limitations of copper and the scaling requirements of AI systems. While microLEDs rely on spontaneous emission and suffer from chromatic dispersion that restricts their reach to approximately five meters, microVCSELs utilize stimulated emission to achieve narrower line widths and reach up to 50 meters. This shift is bolstered by the mature, abundant gallium arsenide supply chain, which contrasts with the manufacturing challenges of indium phosphide and the niche nature of microLEDs. Although microLEDs maintain potential for high-temperature, scale-in applications due to their high bandgap properties, microVCSELs currently provide the necessary speed and design flexibility for modern pluggable cables. This evolution marks a strategic pivot in the industry’s approach to managing the massive data throughput required by next-generation GPU clusters.