Senior Optical Component Validation Engineer

CScale is building the interconnect for gigawatt-scale AI. As AI scale-up moves toward deployments spanning thousands of accelerators and dozens of racks, the network needs to deliver high bandwidth, predictable low latency, and continuous communication. CScale is building integrated optical interconnect designed for this new scale, enabling accelerators to work together like a single, much larger computer. But at this scale, performance is only part of the challenge. Optical failures are inevitable, and the system needs to keep running. CScale is designing the interconnect for continuity. Lasers will fail. Compute shouldn’t. The ambition is simple: Build AI interconnect you can take for granted. CScale came out of stealth in September 2026 with $145 million in Series C funding, bringing total funding to $188 million.

We are looking for a hands-on optical engineer to validate the components that go into our optical engines — semiconductor lasers, silicon photonic devices, and the packaging interfaces that connect them. You will build the measurement methods and test stations that tell us whether incoming parts and assemblies meet their specs, find the physical causes when they do not, and work with our photonics, packaging, and supplier teams to fix them. Good component data is the foundation everything downstream depends on, and you will own it.

Responsibilities

• Define validation plans, specifications-to-test mapping, and acceptance criteria for laser, silicon photonic, and packaging components and interfaces

• Build and run characterization setups for semiconductor lasers: LIV, optical spectrum, side-mode suppression, wavelength versus temperature and current, relative intensity noise, and modulation and extinction performance

• Characterize silicon photonic devices at die and wafer level: waveguide and coupler loss, modulator and photodetector performance, wavelength-dependent behavior, and thermal tuning response

• Develop precision measurement methods for fiber-to-chip and chip-to-chip interfaces — fiber arrays, micro-optics, edge and grating couplers — including insertion loss, alignment tolerance, and polarization dependence

• Correlate component, wafer, and package measurements with optical models to pinpoint the physical causes of excess loss and performance variation

• Define test structures and measurement requirements for new devices and interfaces with the photonics design and packaging teams

• Establish incoming inspection and sampling plans for supplier parts, and correlate measurements with supplier data and across labs

• Support component-level reliability and burn-in testing in partnership with the reliability team

• Automate measurements and build the data pipelines that make component results traceable from supplier lot to assembled engine

• Communicate findings and recommend design, component, or assembly changes to internal teams and suppliers

Qualifications

• Bachelor's degree in Optics, Photonics, Physics, Electrical Engineering, or a related field with 5+ years of relevant industry experience

• Hands-on experience characterizing semiconductor lasers and photonic components in a lab

• Solid understanding of laser physics, Gaussian beam optics, fiber modes, and fiber-to-chip coupling

• Experience with optical test equipment: optical spectrum analyzers, power meters, tunable lasers, polarization controllers, and alignment and positioning stages

• Experience designing experiments and analyzing optical data to find physical root causes, including statistical analysis of component variation

• Python or similar for measurement automation and data analysis

• Clear communicator who works well across engineering disciplines and with suppliers

• Strong ownership mindset with the ability to work in ambiguous and dynamic environments

Preferred Qualifications

• MS or PhD in Optics, Photonics, or Physics

• Silicon photonics device characterization experience, including wafer-level probing

• Optomechanical design experience for characterization fixtures

• Experience with fiber array units, micro-lenses, detachable optical connectors, or active alignment

• Experience qualifying optical components

Compensation includes a base salary of $150,000–$250,000 and equity in CScale. Final offers depend on experience, market conditions and location.