NLIR Shapes the Future of Mid-Infrared Spectroscopy with SFG Technology

Posted  by GoPhotonics

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NLIR, a company specializing in mid-infrared (MIR) spectroscopy and optical sensing, is making waves in the MIR spectroscopy space with its proprietary Sum-Frequency Generation (SFG) process, a transformative approach that addresses the long-standing limitations of traditional MIR systems, including high thermal noise, slow measurement speeds, and bulky designs.

At the core of NLIR’s technology is a nonlinear upconversion process. Instead of detecting MIR photons directly using cryogenically cooled detectors - which are costly, slow, and sensitive to environmental noise - NLIR’s approach converts these photons into visible light. This is achieved by combining MIR photons with a continuous-wave 1064 nm laser inside a specially engineered lithium-niobate (LiNbO3) crystal. The outcome is a single visible-wavelength photon whose energy is the sum of the two original photons, a process known as sum-frequency generation (SFG).

This technique offers two major advantages. First, it enables the use of standard silicon-based detectors, such as CMOS and CCD sensors, which are far more mature, cost-effective, and faster than traditional MIR detectors. Second, and perhaps more critically, SFG naturally suppresses thermal noise. Only MIR photons that are properly aligned and synchronized with the pump laser are upconverted, meaning ambient and internal thermal emissions are largely excluded from the final signal.

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Performance That Redefines Possibility

The implementation of SFG has allowed NLIR to develop products like the MIDWAVE spectrometer series, which offer scan rates from 400 Hz up to 130,000 scans per second. This is a dramatic leap over conventional FTIR systems and allows for MIR spectral measurements on microsecond and even nanosecond timescales, capabilities that were previously out of reach for most spectroscopy platforms. In terms of sensitivity, NLIR’s instruments achieve detection limits in the picowatt-per-nanometer range, even with millisecond-scale exposures. These performance metrics not only match but often exceed those of cryogenically cooled detectors while operating at room temperature.

Real-World Applications

The technology is already gaining traction in industries and research labs around the world. Use cases include:

  • Industrial process monitoring, where real-time gas detection and chemical analysis are essential.
  • Plastic sorting in recycling facilities, where rapid spectral scans help differentiate polymer types on moving conveyor belts.
  • Biomedical diagnostics, such as mid-IR optical coherence tomography (OCT), where live, label-free imaging is enhanced by the technology’s high speed and low noise.
  • Semiconductor analysis, including detection of photoluminescence in mid-IR ranges, enabling new insights into materials like InAs and InSb.
  • Heritage science, where sensitive, non-destructive mid-IR analysis is used to study ancient artifacts and artworks.

A Platform for the Future

SFG Technology is not merely a performance upgrade, it represents a foundational shift in how MIR spectroscopy is designed and deployed. By removing the barriers of cryogenic cooling, high thermal backgrounds, and slow scan rates, NLIR has created a platform that is scalable, compact, and easily integrable into automated workflows.

With a robust roadmap and growing global interest, NLIR is poised to redefine what’s possible in mid-infrared sensing. The company’s technology supports the development of both fixed and portable instruments, and its interface options - including real-time output, inline integration, and smart feedback loops - make it suitable for next-generation manufacturing and research environments.
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