I hear Coherent’s CEO say they’re the world’s only producer of six‑inch indium phosphide, and that the six‑inch platform yields more than four times the chips at under half the cost of the three‑inch standard, coming from three qualified sites in Texas, Sweden and Switzerland. The industry still treats three‑inch as the sensible baseline, noting InP’s brittleness and thermal sensitivity make larger wafers tricky until yields are controlled. In my world, wafer size matters less than disciplined yield‑curve management.