CScale is building the interconnect for gigawatt-scale AI. As AI scale-up moves toward deployments spanning thousands of accelerators and dozens of racks, the network needs to deliver high bandwidth, predictable low latency, and continuous communication. CScale is building integrated optical interconnect designed for this new scale, enabling accelerators to work together like a single, much larger computer. But at this scale, performance is only part of the challenge. Optical failures are inevitable, and the system needs to keep running. CScale is designing the interconnect for continuity. Lasers will fail. Compute shouldn’t. The ambition is simple: Build AI interconnect you can take for granted. CScale came out of stealth in September 2026 with $145 million in Series C funding, bringing total funding to $188 million.

A high-density III-V laser array is a critical integrated component in our broader optical system, and getting it right — in terms of device performance, reliability, and field lifetime — is foundational to everything we ship. In a small, cross-functional team where each engineer's work is directly visible in the product, the FA and reliability function plays an outsized role in translating device physics into field-ready hardware at scale. We are seeking a Senior Laser Design Engineer with a focus on failure analysis and reliability qualification to bridge device design and product readiness — combining rigorous statistical analysis of device test data with physical failure analysis and structured reliability programs to diagnose failure modes, establish field lifetime, and drive design improvements. The right candidate is as comfortable mining wafer-level test distributions for failure signatures as they are directing a FIB cross-section, and communicates findings with the clarity needed to drive corrective action across engineering and foundry partners.

Responsibilities

• Analyze statistical device test data — wafer maps, LIV distributions, parametric yield trends, and reliability screening results — to identify failure signatures, isolate root cause hypotheses, and prioritize physical failure analysis efforts; develop and maintain data analysis workflows that connect test outcomes to device[1]level and process-level root causes.
• Define and recommend FA-focused device tests, process control monitor (PCM) structures, and device health checks that provide early warning of reliability-relevant degradation mechanisms; work with design and test teams to ensure these are incorporated into qualification and production flows.
• Lead failure analysis investigations on III-V optical devices: direct and interpret physical analysis using FIB, SEM, TEM, EMMI, OBIRCH, cathodoluminescence, or comparable techniques; present evidence-based root cause conclusions corroborated by both statistical and physical evidence, with device-level corrective action proposals.
• Design, execute, and interpret reliability qualification programs for semiconductor optical devices — HTOL, burn-in, and accelerated life testing — applying knowledge of random and wear-out failure mechanisms, activation energies, and acceleration factors to assess device lifetime and qualification status.
• Translate FA findings and reliability data into actionable feedback for device design, epi specifications, and foundry process parameters; communicate results through FA reports, qualification documentation, and design reviews.
• Collaborate with epitaxy, device design, test, and systems engineering teams to close the loop between failure modes observed in qualification or the field and root causes addressable at the design or materials level.

Required Qualifications

• Demonstrated experience leading failure analysis of III-V semiconductor optical devices: formulating failure hypotheses from statistical test data, directing and interpreting physical failure analysis (FIB, SEM, TEM, EMMI, OBIRCH, cathodoluminescence, or equivalent), and delivering evidence-based root cause conclusions with corrective action proposals.
• Strong data analysis skills applied to device test data: ability to interpret parametric distributions, wafer maps, and reliability screening results to identify failure modes, screen outliers, and build quantitative evidence for FA hypotheses; proficiency with statistical analysis tools such as JMP, MATLAB, or Python for data visualization, DOE analysis, and distribution fitting.
• Experience defining or recommending FA-relevant device tests, PCM structures, and health monitoring checks that provide actionable early warning of reliability-relevant failure mechanisms.
• Working knowledge of reliability qualification methodology: HTOL, burn-in protocols, failure rate modeling, activation energy extraction, and acceleration factor calculation.

Preferred Qualifications

• Practical experience with foundational laser device characterization: LIV measurements and optical spectral analysis as applied to FA and reliability screening workflows.
• Experience defining technical specifications for III-V optical products, with familiarity with driver circuit interoperability and packaging or integration constraints.
• Familiarity with III-V laser device design fundamentals — heterostructure physics, MQW active region behavior, optical waveguiding, and single-frequency cavity design (DFB/DBR) — sufficient to reason about design-level root causes when interpreting failure analysis findings.
• Experience with statistical reliability modeling or Weibull analysis for device lifetime estimation, using tools such as ReliaSoft Weibull++, JMP, or equivalent.
• Experience with optical module or transceiver packaging and related reliability assessments — including solder joint reliability, hermeticity, fiber attachment, and module-level environmental qualification.

Education

Ph.D. or M.S. in Electrical Engineering, Applied Physics, or a closely related discipline with emphasis in semiconductor devices, photonics, or optoelectronics. Candidates with an M.S. and a minimum of 5 years of relevant industry experience in failure analysis or reliability engineering for III-V optical products will be considered.