AI datacenter optics: VCSEL good enough under 50m, Chinese players pivot to ILS over scarce 300mW lasers
bookwormengr · x · 2026-10-19
- In AI datacenters, leaf/spine switch links stay under 50m, so VCSELs (likely microVCSEL) suffice; CW DFB lasers are only mandatory beyond 50m.
- VCSELs have frequency stability issues in NPO near hot ASICs with no DSP, but the "wide and slow" approach (many low-rate lanes) makes it moot.
- Astera showed microVCSEL with Lumentum at OCP; the Western ecosystem is still catching up.
- Chinese players like Huawei use ILS largely because 300mW+ lasers are extremely scarce while 100-150mW ones are easy to source; reports suggest China is far ahead in this area per CDCE/IDCexpo China visits.
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