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! We are seeking a Sr. Staff Engineer, Photonic Link Co-Design to join our Laser Systems Architecture & Engineering team. This is one of the most technically demanding roles at Lightmatter: you will own the end-to-end simulation, co-design, and laboratory verification of photonic-electronic links in Passage™ — from photonic device modeling through to full transceiver channel characterization in silicon. You will build and maintain the high-fidelity simulation infrastructure that links optical device performance to system-level BER and link margin, drive co-design between photonic and analog circuit teams, and close the loop between simulation and lab measurement on every tape-out. This role sits at the center of how Lightmatter ensures Passage links meet performance at every process corner — and is the technical anchor for photonic-electronic integration quality. The right candidate is equally fluent in photonic simulation environments and at a high-speed electro-optic lab bench, and has the seniority to drive architecture decisions with data. Responsibilities • Develop, own, and continuously improve electro-optic  link simulation models covering photonic device, propagation, and channel BER — from electron to photon to electron. • Build multi-physics models that combine  optical propagation (VPI Photonics, Lumerical INTERCONNECT / FDTD, sax), analog circuit behavior (Cadence Virtuoso / Spectre, Verilog-A)) into a coherent link analysis framework. • Execute comprehensive corner analysis, Monte Carlo variation sweeps, and process-voltage-temperature (PVT) studies to bound link margin; generate actionable specification tightening recommendations for device and circuit teams. • Work closely with analog circuit designers to co-optimize transmitter driver and receiver front-end for the photonic device interface; drive joint simulation across the optical-electrical boundary. • Contribute to  photonic link budgets end-to-end: optical power, modulation efficiency, receiver sensitivity, noise floor, and SNR/OSNR margins. • Contribute to simulation-to-silicon closure methodology for Passage optical links; author test protocols, define measurement sequences, and iterate link models against measured data across process splits and device corners. • Identify and diagnose root causes of link performance gaps — distinguishing photonic, electrical, and integration origins — and drive corrective design actions. • Author and review photonic link architectural specifications, co-design interface requirements, and design-entry criteria for photonic and circuit teams. • Contribute to Passage product-level link planning: propose photonic and electronic co-design opportunities to improve link margin, power efficiency, or yield. Requirements: • PhD in Electrical Engineering, Applied Physics, Physics, or a closely related photonics/optics discipline and 5+ years of experience; or MS + 8 years of directly relevant industry experience at a photonic IC, transceiver, or optical interconnect company. • Deep expertise in photonic device physics and system-level optical link design: silicon photonic modulators, Ge photodetectors, passive WDM components, optical amplifiers, and coherent or intensity-modulated link topologies. • Hands-on proficiency with photonic simulation: VPI Photonics, Lumerical FDTD / INTERCONNECT, or equivalent optical propagation and circuit co-simulation tools. • Experience with analog and mixed-signal simulation: Cadence Virtuoso / Spectre, Verilog-A behavioral modeling, or Keysight ADS for electrical-optical co-simulation. • Demonstrated experience developing and executing optical link budgets, corner analyses, and simulation-to-measurement closure workflows. • Demonstrated high-speed lab skills: vector network analyzers (VNA) / S-parameter characterization, optical spectrum analyzers, high-bandwidth real-time oscilloscopes, BER test sets, optical modulation analyzers (OMA), and optical power meters. • Proficiency in Python for simulation scripting, measurement automation, and statistical post-processing. • Excellent written and verbal communication; able to drive architecture and specification discussions with device and circuit teams. • Familiarity with SERDES architecture: equalization topologies (FFE, DFE, CTLE), CDR, and mixed-signal PHY co-design for high-speed interfaces. Preferred Qualifications • Silicon photonics tape-out and post-silicon characterization experience; familiarity with PDK-level device models and extracted simulation vs. measurement correlation. • Exposure to co-packaged optics (CPO), near-package optics (NPO), or optical I/O chiplet integration challenges. • Signal processing knowledge: DSP for optical communications, forward error correction (FEC), or PAM-4 / NRZ / coherent modulation format trade-offs and simulation. • Experience with Monte Carlo and statistical design methodologies in the context of photonic-electronic system co-design. 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. $180,000—$260,000 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.