Senior Software Engineer at Lumilens – Cracow | Jobyssey

ABOUT LUMILENS

At Lumilens we are building the critical photonics infrastructure that powers tomorrow’s AI supercomputing. From chip-to-chip optical interconnects to scalable photonic engines, Lumilens is unlocking a new era of computing faster, cooler, and massively more efficient.

We’re a well-funded startup backed by Mayfield and led by veterans who’ve built and scaled some of the most transformative technologies in the industry. This isn’t incremental innovation, it’s a ground-floor opportunity to rethink the optical layer from the silicon up. You’ll work alongside a team of world-class engineers solving some of the hardest challenges in optics, systems, and scale. Every line of code, every design decision, every breakthrough you help deliver will shape the infrastructure of tomorrow.

If you're looking for mission, momentum, and the chance to make an outsized impact—jump on the rocket ship. We’re just getting started ... and we are building a Team in Kraków!

What You Will Work On

C# / .NET desktop application — Advanced manufacturing software for optical transceiver testing. A GUI application built with MVVM architecture, featuring multi-threaded test execution, instrument resource management, and RPC services.
Hardware integration — Writing drivers and control code for laboratory equipment, managing parallel test execution and handling complex locking across instruments.
Python test scripts & libraries – Our manufacturing software draws the best from both worlds. You will have the opportunity to integrate complex testing functionality based on Python code embedded natively into the .NET application.
Manufacturing scale - You will be developing software that runs on manufacturing lines, producing thousands of units daily.

Required Skills:

5+ years of C#/.NET — experience with GUI (WPF or similar framework), MVVM, async/await, thread safety, and class library design
Strong command of concurrent programming — designing thread-safe systems, avoiding race conditions, and reasoning about execution across multiple threads and processes
Experience with .NET 8 or later
3+ years of Python — OOP, pytest, abstraction-driven design
Solid understanding of clean architecture — separation of concerns, dependency inversion, dependency injection, and testability
MongoDB or similar document database — data modeling, querying, and managing test results at scale
Analytical mindset — proven ability to break down complex multi-component failures, trace issues across process boundaries, and design reliable solutions under ambiguity
Ability to debug remotely without direct debugger access — diagnosing issues via logs, traces, and telemetry

Infrastructure & Tooling

Git & CI/CD fluency — GitHub Actions, artifact pipelines, versioning strategies, and automated deployment to remote Windows machines
Bash and/or PowerShell scripting for automation, remote management, and deployment
Systems-level thinking

Nice to Have

Experience with test and measurement instruments (oscilloscopes, spectrum analyzers, power meters)
Experience with Unit Tests: xUnit, MSTest, etc.
Knowledge of optical communications, photonics, or transceiver technology
Python.net experience
Familiarity with hardware interfaces – serial communication, TCP sockets, low-level protocols and interfaces (I2C, GPIB), and instrument communication standards (SCPI, VISA)
Familiarity with factory/manufacturing software or MES integration

What we offer

Competitive salary commensurate with experience
Professional development opportunities and certification support
Access to cutting-edge technology and cloud platforms
Collaborative work environment with cross-functional teams

*Lumilens is an equal opportunity employer. All qualified applicants will receive consideration without regard to race, color, religion, gender, identity, orientation, veteran status, disability, or any other legally protected status.

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