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Sr. Staff Thermal Engineer

Lightmatter Boston, MA; Mountain View, CA Full-time Photonics Packaging Engineering Posted May 28, 2026
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What it’s like to work at Lightmatter

Photonic AI Computing · Boston

4
Employee Rating
3.5
Work-Life Balance
45
Open Roles
eng-drivenship-fastproduct-impactlearning

What employees love

  • Building genuinely world-changing photonic AI chips with some of the best engineers in the field
  • Flat, collaborative culture where trust and respect are real — not just posters on the wall

What could be better

  • Startup pace with occasional crisis mode — not for those wanting predictable 9-to-5
  • Compensation can lag behind top-tier tech companies despite the cutting-edge work
View full Lightmatter culture profile →

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!

We are seeking a Thermal Engineer with strong expertise in thermal analysis and deep knowledge of semiconductor packaging technologies to join our team. In this role, you will work on leading-edge packaging technologies to enable AI architectures that set new industry standards in compute power, performance, and efficiency. As a part of the package technology team, you will be responsible for leading thermal analysis required for product definitions, driving innovative thermal solutions, and conducting analysis and validation efforts to deliver package and system designs that meet product landing zones. Your work will contribute to advanced package and system designs that meet power dissipation, assembly, and reliability requirements while delivering system-level solutions for leading-edge products in data centers and high-end compute segments.

Responsibilities:



Required Qualifications:

Preferred Qualifications:



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.
$166,000$262,000 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.

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Frequently Asked Questions

What is the work-life balance like at Lightmatter?
Lightmatter has a work-life balance score of 3.5/5 based on employee reviews. This is about average for the AI/tech industry.
What is Lightmatter’s culture like?
Lightmatter is characterized by these culture values: eng-driven, ship-fast, product-impact, learning. Based on employee reviews, the company has an overall rating of 4/5. Building genuinely world-changing photonic AI chips with some of the best engineers in the field
How many open roles does Lightmatter have?
Lightmatter currently has 45 open roles across departments including engineering, product, sales, and more. Roles are refreshed daily from their careers page.
Is this role remote-friendly?
This role is located in Boston, MA; Mountain View, CA. Check the job description above for specific location and remote work details.
Apply for this role at Lightmatter →