Lightmatter is leading the revolution in AI data center infrastructure, enabling the next giant leaps in human progress. The company invented the world’s first 3D-stacked photonics engine, Passage™, capable of connecting thousands to millions of processors at the speed of light in extreme-scale data centers for the most advanced AI and HPC workloads. Lightmatter raised $400 million in its Series D round, reaching a valuation of $4.4 billion. We will continue to accelerate the development of data center photonics and grow every department at Lightmatter! If you're passionate about tackling complex challenges, making an impact, and being an expert in your craft, join our team of brilliant scientists, engineers, and accomplished industry leaders. Lightmatter is (re)inventing the future of computing with light! At Lightmatter, an SDET is a software engineer first , not a QA coordinator or manual tester. You'll design and build the frameworks, harnesses, and hardware-in-the-loop infrastructure that let firmware engineers test their own code continuously on real photonic hardware. You'll sit with the firmware team, spend time at the bench with oscilloscopes, debuggers, and optical instruments, and serve as the bridge between firmware and broader software and systems organizations. Responsibilities • Own the architecture and roadmap of the firmware test automation framework across products, targets, sites, and teams • Design and build stable automation for new firmware features and hardware, held to production-quality engineering standards • Build and operate HIL test infrastructure: bench and rack fixtures, device farms, power/reset control, instrument integration, and CI orchestration on real photonic hardware • Define test strategy, plans, and reporting; lead test plan reviews across teams • Integrate firmware testing into CI/CD so every change is built, flashed, exercised on hardware, and reported automatically • Own framework reliability and flaky test metrics as first-class engineering problems • Build results, telemetry, and log pipelines for triage, trend analysis, and release decisions • Debug failures across the full stack (firmware, board, instrument, fixture, test code) and partner with engineers to resolve them • Participate in firmware design reviews to influence testability and diagnostics early • Integrate with data center management interfaces (CMIS, OpenBMC, DMTF); debug embedded systems using GDB, JTAG, and logic analyzers • Define diagnostics and monitoring architecture for photonic transceivers • Mentor engineers on test architecture and write clear documentation for non-specialists Qualifications • 8+ years of professional software development, primarily on embedded products, including designing test frameworks and infrastructure • BS or MS in Computer Science, Electrical Engineering, or equivalent experience • At least one automation framework or HIL system architected and built from scratch, adopted by other engineers, and in daily use  and the ability to discuss its design, tradeoffs, and lessons learned • Strong Python: fixture and abstraction layers, hardware drivers, plugin/configuration architectures • Working fluency in embedded C/C++: able to read firmware drivers or state machines and write tests for edge cases • Experience owning CI/CD pipelines running tests on physical hardware (GitHub Actions, GitLab CI, Jenkins, or equivalent), including runner health, hardware allocation, and recovery • Track record of delivering robust automation under fast-changing requirements and hardware Preferred Qualifications • PhD, or MS with 8+ years in embedded test automation or firmware development • Experience testing firmware for optical transceivers, photonic systems, or precision analog/mixed-signal hardware • Familiarity with CMIS, OpenBMC, or DMTF/Redfish • Experience with Pytest ecosystem and test tooling for Zephyr or FreeRTOS (Twister, ztest, Renode, QEMU, or similar) • Experience with optical and electrical test and measurement equipment • Startup experience • Thoughtful use of AI-assisted tools in test generation, triage, or analytics We offer competitive compensation. The base salary range for this role determined based on location, experience, educational background, and market data. Salary Range: total compensation goes beyond base salary, it also includes a new hire equity grant, annual performance-based equity, and other rewards that recognize your impact and contribution. $178,000—$225,000 USD Benefits • Comprehensive Health Care Plan (Medical, Dental & Vision) • Retirement Savings Matching Program • Life Insurance (Basic, Voluntary & AD&D) • Generous Time Off (Vacation, Sick & Public Holidays) • Paid Family Leave • Short Term & Long Term Disability • Training & Development • Commuter Benefits • Flexible, hybrid workplace model • Equity grants (applicable to full-time employees) Benefits eligibility may vary depending on your employment status and location. Lightmatter recruits, employs, trains, compensates, and promotes regardless of race, religion, color, national origin, sex, disability, age, veteran status, and other protected status as required by applicable law. Export Control Candidates should have capacity to comply with the federally mandated requirements of U.S. export control laws.