Lightmatter, a photonic computing startup, has successfully raised $400 million to enhance the efficiency of modern datacenters. The company's innovative optical interconnect layer allows hundreds of GPUs to operate in unison, addressing significant bottlenecks in AI model training. As demand for high-performance computing surges, Lightmatter's technology promises to improve data transfer speeds and reduce latency. With major datacenter players already showing interest, the startup is positioned for rapid growth. This funding round values Lightmatter at $4.4 billion, highlighting its potential in the evolving tech landscape.