This is a good read about 6 inch Gaas Vcsels and what the U.S Government is looking for.

So critical and time-sensitive are these optical systems

that the US government has recently announced a photonics

manufacturing initiative to scale production capacity, reduce

component costs and assure a stable, US-based supply chain.

6-inch VCSEL production uses a more advanced wafer

fabrication tool set and epi growth systems that provide

better cross-wafer uniformity, controllability and ultimately

better yields and costs.

David Cheskis, Ph.D.

CS MANTECH Conference, May 18th - 21st, 2015, Scottsdale, Arizona, USA

http://www.csmantech.org/Digests/2015/papers/2.4-011.pdf