About the role
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 hiring a senior engineer for our Photonics Characterization team at Lightmatter. Lightmatter is redefining computing by building photonic systems that use light to enable high-bandwidth, energy-efficient AI computing. In this role, you will lead advanced characterization, bring-up, validation, and root-cause analysis of semiconductor lasers, tunable laser sources, DFB lasers, external-cavity lasers, laser diodes, and semiconductor optical amplifiers. This role requires strong hands-on lab expertise, deep understanding of laser physics and semiconductor device behavior, and the ability to connect measured device performance to design, packaging, system, and reliability implications. You will own complex optical and electro-optical test setups, develop robust measurement methodologies, automate characterization flows, analyze large datasets, and translate results into clear engineering conclusions. You will also work closely with laser design, photonics, packaging, systems, reliability, and software teams to guide device development from early engineering samples through production-oriented validation.
Responsibilities Lead hands-on characterization of semiconductor lasers, tunable laser sources, DFB lasers, DBR/ECL lasers, laser diodes, and semiconductor optical amplifiers. Measure and analyze key laser and SOA performance metrics, including output power, wavelength, optical spectrum, SMSR, RIN, linewidth, gain, saturation power, ASE, noise figure, tuning behavior, optical stability, wavelength stability, and thermal sensitivity. Develop advanced LIV, L-I-V-T, wavelength tuning, power stability, RIN, SMSR, linewidth, and long-term drift measurement methodologies. Characterize devices across current, voltage, temperature, optical loading, polarization, optical feedback, aging, and operating conditions. Analyze SOA gain, gain saturation, wavelength-dependent gain, polarization-dependent gain, ASE noise, carrier dynamics, thermal behavior, and nonlinear effects. Build, validate, and maintain automated optical and RF measurement setups using Python, PyVISA, LabVIEW, MATLAB, or similar tools. Use modeling and design-analysis software to support characterization planning and data interpretation, including tools for laser physics, optical gain, rate-equation analysis, thermal modeling, optical spectrum analysis, and system-level performance estimation. Develop scripts and software workflows for instrument control, automated data collection, calibration, data processing, visualization, statistical analysis, and automated reporting. Debug complex optical, electrical, RF, and thermal measurement issues, including optical coupling, polarization sensitivity, back-reflection, RF noise, grounding, calibration error, thermal drift, and instrument limitations. Define measurement best practices, calibration procedures, data quality checks, and test documentation standards. Translate characterization results into actionable feedback for laser design, photonics integration, packaging, system architecture, and reliability teams. Support device bring-up from early engineering samples through mature validation and production-readiness phases. Mentor junior engineers and help establish high-quality characterization practices across
