System Mechanical Design Engineer

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! About this Role We are seeking a motivated, dedicated, and hands-on mechanical design engineer to help develop a chassis and rack platforms for the next-generation artificial intelligence server alongside a team of world-class scientists and engineers. As a Mechanical Engineer at Lightmatter, you will sit at the critical intersection of silicon photonics, advanced 3D packaging, and extreme-density thermal management. You won't just be tweaking existing designs; you will be the practical execution engine transforming complex electro-optical concepts into scalable, manufacturable hardware. While this role focuses on flawless technical execution rather than top-level project architecture, your hands-on impact will be immense. You will navigate the transition from initial CAD and prototype builds to leading external Contract Manufacturers (CMs). If you are a rigorous, detail-oriented engineer eager to solve complex thermal-mechanical packaging puzzles, orchestrate supply chains, and build the physical backbone of next-generation AI infrastructure, we want you on our team. Responsibilities Design, test, analyze, integrate, qualify and document hardware of moderate to high complexity, in a dynamic startup environment. Ensure proper packaging of optical, electrical and related components for optimal thermal performance. Responsible for mechanical design from generating CAD and drawings, to BOM generation and crafting work instructions. Fully understand project requirements and timelines while identifying gaps and drive to closure with the stakeholders Initiate and drive design reviews while managing the resulting feedback and change requests. Collaborate in root-cause-analysis and technical investigations with cross-functional teams. Drive hands-on in-house build and integration activities, scaling from initial prototype fabrication to leading external CMs for high-volume production. Manage outside fabricators to ensure correct build-to-print and quality workmanship. Work with technical program managers to define a detailed timeline. Actively mitigate and manage lead-time issues with the supply chain team. Collaborate with relevant cross-functional engineering teams to understand dependencies. Provide assistance to creating technical road-maps, establishing best practices, and determining product feasibility. Qualifications Bachelor’s degree in Mechanical Engineering or related fields 5+ years of experience in system mechanical design with multiple successful product releases Proficient in a 3D CAD solid modeling software package such as SolidWorks Familiar with both thermal and structural testing and analysis Experience with state-of-the-art mechanical engineering design and analysis tools (ANSYS preferred) Possess a strong understanding in the application of heat transfer principles, strength of materials, materials selection, design for vibration environments and the ability to apply those principles to unique mechanical design challenges. Industry experience in electronics packaging Strong communication and adaptive in execution Preferred Qualifications Master’s degree in Mechanical Engineering or related field Familiar with 3