Who makes external laser sources for AI data centers

Co-packaged and silicon-photonic designs move the optics next to the switch or accelerator die, but they mostly do not move the laser. Silicon does not emit light efficiently, so the laser is built in a different material system and supplied separately — either as a discrete source mounted nearby or as a remote source feeding light in over fibre, which is what this part covers. Keeping the laser external is a deliberate engineering choice, not an interim step. Lasers are the part of an optical link most sensitive to heat and the most likely to fail, and putting them next to a hot switch ASIC is the worst place for both problems. An external source can be cooled on its own terms, replaced without touching the package, and in some designs shared across many lanes. This makes the part a genuine dependency for the whole co-packaged optics story rather than a detail of it: a switch vendor moving to co-packaged optics is taking on a laser supply relationship it may not have had before. The suppliers are the compound- semiconductor laser makers, a much shorter list than the transceiver market they sell into. What to look for is whether a given architecture uses discrete or remote sources, and how many lanes one laser feeds — that ratio decides whether this part scales with ports or with racks.