Fiber Network Engineer

Anthropic•San Francisco, CA

15h•Hybrid

About The Position

Anthropic is building Anternet — a private, global dark-fiber backbone connecting our data centers, cloud regions, and partners. We light our own glass: long-haul and metro DWDM over leased dark fiber and IRU pairs, terrestrial and subsea, terminating on our own optical line systems and routers. We're looking for a Fiber Network Engineer to own the physical layer of this network end-to-end. You'll be the person who decides where the fiber goes and then makes sure it actually shows up, splices clean, and tests to spec. This is equal parts route engineering, vendor management, and field-delivery program management — the connective tissue between "we need N×Tbps between these two metros" and "the span is lit and carrying traffic." This is a foundational role building Anternet's fiber program from the ground up. You'll define the inventory system, set acceptance standards, and establish the vendor bench yourself. You'll work closely with our optical/transport engineers (who design the line systems on top of your fiber), our backbone routing team, and our data center and capacity planning teams.

Requirements

Experience in OSP/fiber planning or network delivery at a carrier, hyperscaler, dark-fiber provider, or large enterprise backbone
Demonstrated experience taking long-haul or metro dark-fiber routes from design through acceptance — can read an OTDR trace and engage substantively with vendors on splice quality
Solid working knowledge of the vendor landscape: who has conduit where, how IRU vs. lease vs. wavelength pricing behaves, and what's negotiable in an MSA
Proficiency with GIS/KMZ tooling for route design and comfort maintaining structured inventory data
Sufficient understanding of optical transport (DWDM, amplifier spacing, span loss, CD/PMD) to design fiber that line-system engineers can use
Ability to serve as the single accountable owner for physical delivery across many concurrent builds

Nice To Haves

5+ years of OSP/fiber planning or network delivery experience
Subsea experience: CLS builds, wet-plant IRU negotiation, consortium dynamics
Experience standing up a fiber program from near-zero — building the inventory system, acceptance standards, and vendor bench from scratch
Familiarity with permitting, ROW, and make-ready processes in US metro markets
Scripting or light tooling experience (Python, Go, SQL, or similar) for inventory and reporting workflows
Comfort with occasional travel for site surveys, CLS/ILA walks, and vendor meetings

Responsibilities

Route engineering and design — Plan terrestrial and subsea fiber routes between Anternet PoPs and data centers. Evaluate diversity (SRLG, conduit, ROW, landing-station separation), latency, and OSNR/loss budgets. Produce route KMZs, splice diagrams, and as-built documentation
Fiber acquisition — Source and qualify dark fiber, IRU, and wavelength options from carriers and infrastructure providers. Run RFPs, compare bids on cost, route quality, diversity, and MTTR, and drive contracts to signature alongside legal and procurement
Vendor and delivery management — Own the build from PO to acceptance: track splicing, lateral construction, building entries, meet-me-room cross-connects, and CLS access. Hold vendors to schedule and SLA; serve as the escalation point when a span is late or fails OTDR
Acceptance and characterization — Define and enforce fiber acceptance criteria (OTDR bi-directional, IL/ORL, CD/PMD where relevant). Review test results, reject substandard spans, and sign off on handover to the optical team
Capacity and lifecycle management — Maintain the source-of-truth fiber inventory (strands, conduits, splice points, leases, IRU terms and renewals). Forecast fiber needs against our PoP and capacity roadmap. Monitor degradation and quality over time
Operations — Partner with NOC and field-ops on fiber cuts, locates, and repairs. Drive root-cause analysis with vendors and feed lessons back into route-diversity decisions