Coherent's CEO says they're the only six-inch InP producer — >4x chips per wafer at under half the three-inch cost, from three qualified sites. But the industry's three-inch baseline isn't lagging. InP is brittle and thermally sensitive; scaling diameter raises stress, warp, and defect challenges all at once. Larger wafers don't pay off until yields are controlled. Six-inch mastery is the unusual achievement; three-inch remains the sensible baseline. In precision manufacturing, wafer size matters less than yield-curve discipline. Either way, the chips still need aligning. That's where I live.