The drive current of a mid-infrared laser at 3329 nm is modulated in amplitude at 1 kHz and the ultra-fast 80 kHz edition of the NLIR 2.0 – 5.0 µm spectrometer measures the laser spectrum with a temporal resolution of 12.5 µs. When the drive current is modulated, the amplitude and center frequency of the laser changes, and these characteristics are clearly visible in the data shown in the figure.  

Measurement done by Marc-Simon Bahr at HAW Hamburg, Department of Information and Electrical Engineering. 

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Our fast infrared spectrometers are ideal to measure transmission properties of IR coated windows or mirrors. The figure shows single-shot measurements (20 ms exposure time using a standard 30 W thermal light source) of a Germanium band-pass filter and a 1064 nm mirror with AR coating for mid-infrared wavelengths.

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coating quality contro measurement


A new Optics Letter reports on mid-infrared optical coherence tomography
(OCT) at 4 µm based on NLIR upconversion spectrometer technology, which promotes the scan rate to 3 kHz, thus enabling  for the first time real-time OCT monitoring in the mid-infrared.

Niels M. Israelsen et al., Opt. Letts. 46, p. 4558 (2021).

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Light from an NKT Photonics MIR Compact supercontinuum source, which emits 5 ns pulses at 40 kHz covering a spectrum from 2 µm to 4.2 µm, is measured using two different point detectors. A MIR monochromator selects the wavelength 2.4 µm with a 20 nm bandwidth, and the output is coupled to a 200 µm MIR fiber. The output of the fiber is sent in turn to each of two detectors: an NLIR 240 MHz 2.4 µm Single-wavelength detector (with 50 dB attenuation) and a commercially available 9 MHz InAsSb detector with direct exposure. The figure shows the responses of the two detectors.

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Our customers say

We are very satisfied with the outstanding performance of the NLIR up-converter-spectrometer combination in terms of both sensitivity and spectral range. These advantages allow us to develop a versatile broadband (>600 cm-1) trace gas sensor. Promising sub-ppm sensitivity for single species has been recently achieved, and fast and stable multi-species detection is well within reach. We are also impressed by the excellent custom service of NLIR, in particular its transparency for knowledge sharing; we enjoyed working together with the innovative technical team of NLIR. Associate Professor Dr. Frans J. M. Harren & Dr. Qing Pan, Radboud University

“NLIR provided professional assistance and transparency for knowledge sharing. I’m definitely satisfied with the improved performance of NLIR up-converter module and the scientific collaboration with the technical NLIR team.”Marie-Curie COFUND Postdoc Dr. Alessandro Trenti, University of Vienna


Mid-infrared spectrometers and detectors – a new paradigm

The fastest infrared detectors on the market
➢ 130 kHz full-spectrum spectroscopy
➢ 10 GHz bandwidth point detection

A new standard for sensitivity and responsivity
➢ Noise-equivalent power of few fW/√Hz
➢ Up to GV/W response

Bandwidth flexibility
➢ 2.0 – 5.0 µm and 7.6 – 12.0 µm
➢ The narrower the bandwidth, the higher the response

See our products

See our spectrometers, point detectors, and conversion module; all the devices are outstanding in sensitivity, speed and noise performance.

Read about our technology

The enabling technology of NLIR is upconversion of mid-infrared wavelengths to near-visible wavelengths. This key optical process allows detection of mid-infrared light by Si or GaAs detectors, which are far superior in terms of detectivity, speed, and noise

What are our products used for?

Our products have a wide range of applications from ultra-sensitive or rapid power detection and spectral analysis of light sources to measurement of different kind of samples, for example plastics, optical coatings, components in water and oil solutions, and mixes of gases.

The core of the NLIR technology

All mid-infrared detection products of NLIR are based on sum-frequency generation (or upconversion), which is a highly sophisticated nonlinear optical process where two-photons annihilate in the creation of a new photon with the same energy as the sum of the originals . When mid-infrared light enters one of our detectors, it is brought together with a high-power 1064 nm laser inside a LiNbO 3  crystal; one photon from each of these fields annihilate by interacting with bound electrons in the crystal to create a photon in the near-visible range. The new photon exits the crystal and can now be measured using Silicon-based devices. In the conversion process, all properties of the mid-infrared photon, except the wavelength, are conserved.

nlir technology nonlinear process


Lasse and Søren, NLIR’s experienced optics-engineer duo, are showing a simple measurement of a nano-second pulse at 3.8 µm from a super-continuum source. The pulse has a peak power of only 0.5 µW but the response of the detector is 3 kV/W so the oscilloscope can easily measure the signal without further amplification.

Free Spectrometer Software included

  • Easy connect and use software included. 
  • Data live stream, external trigger mode, background capture, transmission view, data saving, etc. 
  • API for spectrometers in MATLAB and Python available upon request.
Spectrometers software in MATLAB and Python
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