Senior Photonics Circuit Design Engineer

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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! The Laser System Architecture & Engineering (LSAE) team is seeking a Photonics Circuit Design Engineer. The candidate will design and model the photonic and analog sub-circuits that make up Lightmatter's Guide™ laser products and Passage™ optical links. Examples include the laser source and wavelength-locking blocks, ring filter and modulator banks, mux/demux, optical power splitting and monitoring, and the photodetector-receiver front end. You will own the bridge between device physics and sub-circuit behavior. You will build high-fidelity behavioral models that capture fabrication variability, dispersion and thermal effects. From them you will assemble sub-circuit models that accurately predict how each block performs. Systems architects will build their end-to-end product simulations on your models, so your models must be accurate, correlated to silicon, and ready to plug into larger simulations. Responsibilities • Construct and maintain high-fidelity compact and behavioral representations for both active and passive silicon photonic elements, covering waveguides, couplers, MZIs, micro-rings, multiplexers, phase control elements, thermal tuners, modulators, detectors, and integrated III-V/SOA components. • Incorporate process variations (waveguide geometry and etch biases), dispersion metrics, thermal-optical tuning characteristics, and non-linear properties directly into component modeling. • Partner with device engineers to extract and calibrate parameter sets using optical solvers (FDTD, EME), foundry process design kits, and physical silicon data across various tapeouts to ensure high model correlation. • Architect and deliver comprehensive sub-circuit simulations for Guide laser modules, encompassing optical sources, gain media, wavelength control loops, power distribution trees, monitors, and associated analog interfaces (TIAs, converters). • Implement integrated sub-circuit models for Passage interconnect blocks, including modulated ring arrays, filter banks, thermal controls, drive circuits, DWDM MUX/DEMUX structures, and receiver front-ends. • Refine sub-circuit topologies against core key performance indicators such as insertion loss, extinction ratio, signal isolation, tuning efficiency, operating bandwidth, and noise performance in collaboration with circuit and device teams. • Execute corner, statistical Monte Carlo, and margin analyses to establish component tolerances, evaluate yield metrics, and inform experimental test vehicle vehicles and architecture reviews. • Validate and iterate sub-circuit behavioral representations based on empirical silicon measurements across production cycles. Required Qualifications • Ph.D. in Electrical Engineering, Applied Physics, Photonics, or related discipline plus 2+ years of industry experience (or M.S. with 5+ years). Staff level targeting Ph.D. with 6+ years or M.S. with 10+ years. • Deep background in silicon photonic physics and analog circuit fundamen

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