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 the team. • Prepare clear technical reports, design reviews, data summaries, and recommendations for cross-functional engineering teams. Qualifications • PhD or Master’s degree in Electrical Engineering, Physics, Applied Physics, Photonics, Optics, or a related technical field. • 5+ years of hands-on experience in semiconductor laser, SOA, photonics, or optical device characterization. • Strong understanding of semiconductor laser physics, optical gain, carrier dynamics, rate equations, thermal effects, feedback sensitivity, linewidth, RIN, and optical noise mechanisms. • Deep hands-on experience with optical and electro-optical lab measurements. • Strong familiarity with laser characterization metrics such as threshold current, slope efficiency, wall-plug efficiency, LIV curves, SMSR, RIN, linewidth, wavelength tuning, optical spectrum, power stability, and wavelength stability. • Strong understanding of semiconductor optical amplifiers, including gain, saturation behavior, ASE, noise, carrier dynamics, polarization dependence, wavelength dependence, and thermal effects. • Experience operating optical and RF instruments, including laser current drivers, TEC controllers, OSAs, optical power meters, photodetectors, RF spectrum analyzers, oscilloscopes, bias tees, optical filters, polarization controllers, optical switches, and fiber-coupled components. • Strong Python programming experience for instrument automation, data analysis, plotting, statistical analysis, and automated reporting. • Experience using software tools for device design support, modeling, simulation, or data-driven analysis. • Strong analytical skills and ability to debug open-ended device, setup, and measurement problems independently. • Ability to communicate complex technical results clearly and drive conclusions across design, characterization, packaging, and systems teams. Preferred Qualifications • PhD in Electrical Engineering, Physics, Applied Physics, Photonics, Optics, or a related field. • Prior experience characterizing DFB lasers, DBR lasers, tunable lasers, ECLs, laser diodes, or SOAs for integrated photonics or optical communication systems. • Experience with advanced laser-noise measurements, including RIN, linewidth, phase noise, frequency noise, optical feedback sensitivity, and relaxation oscillation analysis. • Familiarity with laser and SOA modeling, including rate-equation modeling, gain modeling, thermal modeling, optical feedback analysis, and wavelength tuning behavior. • Experience using commercial or internal simulation/design tools for photonic device analysis, laser design support, or system-level optical performance modeling. • Experience with III-V semiconductor materials, heterogeneous integration, laser packaging, fiber coupling, optical isolators, and thermal control. • Experience with high-speed optical or RF measurements involving fast photodetectors, RF spectrum analyzers, oscilloscopes, LNAs, bias tees, and calibration/de-embedding. • Experience developing automated test platforms for device characterization and validation. • Experience analyzing large characterization datasets and creating automated dashboards or reports. • Experience supporting reliability, qualification, or production-oriented validation of semiconductor lasers or optical amplifiers. • Demonstrated ability to lead technical work independently, define test strategy, mentor junior engineers, and influence cross-functional engineering decisions. 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…