Technology giants are continuing to expand AI computing infrastructure, driving demand for high-performance optical interconnect components. US optical communications leaders Coherent and Lumentum are actively developing 6-inch indium phosphide (InP) wafer production technology. Industry sources said 4-inch wafers remain the mainstream format, but fast-growing demand in optical communications is accelerating the shift toward 6-inch substrates. Supply constraints, however, persist, with substrate technology maturity and supply availability cited as the main bottlenecks.