Nonlinear Infrared Sensors

NLIR is a start-up company founded by 3 researchers at the Department of Photonics Engineering at the Technical University of Denmark (DTU Fotonik) and NLIR’s CEO. NLIR is based on the novel patented upconversion technology invented by its founders at DTU Fotonik.

The core of the upconversion technology is a non-linear crystal that converts mid infrared light to near visible light. This enables the use of fast and efficient Silicon based sensors for detection of MIR light.

The non-linear mid infrared spectrometer implementation represents a revolutionary new measurement paradigm. The company is named Non-Linear InfraRed sensors (NLIR) to highlight the products technological difference from todays leading MIR spectrometry method of Fourier-Transform InfraRed spectroscopy (FTIR).

NLIR target at several industry sectors: Oil and gas, Polymer, Food and Agriculture, Pharmaceutical, Chemical, Medical Diagnostic and Environmental.

MIR Spectrometers

NLIR_S2050 MIR_Mid-Infrared Spectrometer

The NLIR 2.0 – 5.0 µm Spectrometer S2050 is based on a novel measurement scheme that upconverts the MIR light to near-visible light. Silicon-based near-visible light detectors are far superior to MIR light detectors in terms of detectivity, speed, and noise. The NLIR upconversion technology, therefore, brings these attractive features and the advantages that follow, to the MIR regime.

Both editions have sensitivities at -80 dBm/nm or better, and the maximum full-spectrum readout rate is 130 kHz! As a result, the spectrometer enables the characterization of light sources and measuring spectral content from chemical processes with a time resolution of less than 10 µs.

The NLIR S2050 spectrometers cover a broad part of the MIR spectrum where the spectral fingerprints of many C-H bonds of gases are located together with those of a number of other common gases. Many plastics (independent of color) also absorb in this MIR region, which makes indentification easily accessible

  • Broadband operation from 2.0 - 5 µm
  • Up to 130 kHz full-spectrum read out rate
  • Down to 5 pW/nm sensitivity
  • 6 cm-1 resolution on 2048 pixels

Key applications:

  • Black plastic sorting
  • Gas concentration measurements
  • Polymer identification
  • Petrochemical analysis
  • Broadband IR coating quality control
  • MIR super-continuum light measurements



NLIR S2050 MIR Spectrometer Datasheet.pd
Adobe Acrobat Dokument 973.6 KB

MIR Detectors

NLIR_D2250_Single Wavelength Detector

The NLIR MIR light detector is based on a novel measurement scheme that upconverts the MIR light to the near-visible regime. Near-visible light detectors  (based on for example Si) are far superior to MIR light detectors in terms of efficiency, speed and noise.

  • Single-wavelength detection from 2.2 - 5.0 µm
  • Tuning optional
  • Down to 10fW/√Hz noise-equivalent power
  • DC - 10 GHz bandwith
  • Plug-and-play
  • Based on novel upconversion technology

Key applications:

  • Nanosecond pulse characterisation
  • Low-power MIR light detection
  • Detection of gas lines
  • Free-space communication
  • DIAL (differential absorption LIDAR)
  • Chemical kinetics

Near-visible light detectors exist with many different combinations of specifications  and what detector to choose depends on the desired application.


NLIR D2250 MIR Detector Datasheet.pdf
Adobe Acrobat Dokument 693.1 KB


The prototype S76120 MIR_Spectrometer

NLIR is expanding its technological framework into longer wavelength regions, currently 7.6 µm – 12.0 µm.

The spectrometer has free-space input and is therefore best utilized to analyze samples with a fixed, known light source like a conventional FTIR instrument.

The spectrometer is highly sensitive with typical exposure times of tens of milliseconds for an entire spectrum using a 30 W thermal lightsource. The resolution is 8 cm-1 – 10 cm-1. This spectrometer is optimal for at-line or in-line monitoring of, for example, liquid based samples in out-of-laboratory environments.

The spectrometer is currently available with a 50 Hz full-spectrum readout rate and a resolution of 10 cm-1. The sensitivity is 200 pW/nm (-67 dBm/nm) with full aperture exposure.


S76120 Prototype Spectrometer

S76120-50 or S76120-130k

Spectral Range          7,6 - 12.0 μm

SNR @ 1 s                 ~ 6.000 (depending on light source)

Resolution                 10-12 cm-1 

Min. exposure time     1-1000 / 0.0013 - 0.654 ms

Maximum spectrum readout rate  50 Hz/ 130E3 Hz

Optical input              Free space

Connection                Ethernet

Measurement options Transmission, ATR

Bit depth                   14 bit / 12 bit

Dimensions (H×L×W) 100x306×200 mm

Datasheet NLIR S76120 MIR Spectrometer (Prototyp)
Adobe Acrobat Dokument 809.8 KB

MIR light source

L1280 Fiber-coupled MIR light source


       Product Overview

  • 1.2 – 8.0 μm wavelength range
  • > 5 mW power in 500 μm fiber
  • Stability better than +/- 0.5%
  • 5,000 hours lifetime
  • Active cooling
  • Fiber-coupled


Thermal infrared light source directly to your sample in an optical fiber.

Infrared light or infrared radiation sources are used in a variety of applications and measurements. Compared to other light sources, high-temperature IR light sources are relatively cheap and require only simple electronics; they emit high-power light that is stable and reliable. However, due to the nature of the warm emitter, the light is incoherent and emitted in all directions, which makes it difficult to guide and focus the light onto a sample with high intensity.

NLIR’s fiber-coupled IR light source makes it easy to bring MIR light to a sample either by positioning the fiber tip close to the sample or by using one of the many commercially available fiber-probes.

The light source is plug-and-play, turns on in a few seconds, and is actively cooled so that no parts are too warm to touch.