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xAI is seeking an Optical Engineer to own the physical optical layer of AI training and inference compute clusters. You will design and deploy fiber-optic interconnects at scale, working within a cross-disciplinary Data Center Engineering team that designs compute clusters from first principles, pushing thermal, electrical, and optical systems to their limits.
Key responsibilities include:
- End-to-end optical and fiber design for AI training/inference fabrics: fiber cabling, cassette/panel architecture, polarity, breakout, reach, and connector strategy (MPO-12/16, SN, MDC, LC, OSFP/QSFP-DD)
- Write and verify link budgets for scale-out and scale-up interconnect (SMF/MMF, AOC/DAC, DR/FR/LR, InfiniBand and Ethernet), including loss, reflections, FEC, and realistic install margins
- Develop and implement factory tests for optical interconnects including insertion loss, return loss, and polarization
- Select and qualify optics, fiber, and connectivity; own vendor bring-up, failure analysis, and fleet reliability
- Deploy and verify end-to-end optical interconnect into the manufacturing line
- Lead commissioning and debug using inspection/cleaning, power meter, OTDR, BER/FEC stats, and volume failure mode analysis
- Evolve connectivity toward next-generation speeds and density (800G/1.6T, CPO/NPO awareness)
- Collaborate with mechanical and network teams on structured cabling, raceways, tray fill, bend radius, pre-term vs field-term strategies, and labeling at hall scale
The company operates with a flat organizational structure where all employees are hands-on contributors. You will be expected to work extended hours and weekends as needed to support design releases, line bring-up, and cluster deployments. Travel to manufacturing and datacenter sites is required, as is the ability to work in active datacenter and factory environments.
REQUIREMENTS:
- Bachelor's degree in electrical engineering, optical engineering, physics, or related engineering discipline
- 2+ years of professional experience in fiber layout, optical link design, and/or datacenter/HPC optical engineering
PREFERRED EXPERIENCE:
- Demonstrated ownership of fiber or optical design installed and turned up in a datacenter, HPC, or AI-compute environment
- Working knowledge of single-mode vs multimode, MPO polarity, insertion/return loss, and 100G+ transceiver classes
- Hands-on optical test experience: inspect/clean, power meter, OTDR or equivalent
- Fiber interconnect ownership for AI/high-compute clusters (GPU scale-out fabric, InfiniBand NDR/XDR, RoCE Ethernet 400/800G)
- High-density pre-terminated trunk/cassette design and rack-to-spine optical mapping at hall scale
- Optics vendor qualification at volume (OSFP, 800G DR8/2xFR4, AOCs, and real-world fleet failure modes)
- Experience designing optical harnesses or cassettes for manufacturing lines, including test coverage and yield
- DWDM/campus DCI for cluster-to-cluster or building-to-building connectivity
- Familiarity with CPO/NPO, linear-drive optics, and next-gen packaging
- Background at a high-velocity AI cloud, GPU cloud, or custom-compute hardware team
