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


The NLIR S2055 spectrometer covers 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 - 5.5 µm /1818-5000 cm-1
  • Entire spectrum in milliseconds
  • Very robust - no moving parts
  • Based on novel upconversion technology

Key applications:

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



NLIR S2055 MIR Spectrometer Datasheet.pd
Adobe Acrobat Dokument 391.0 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.


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)
NLIR S76120 MIR Spectrometer Datasheet.p
Adobe Acrobat Dokument 439.2 KB

MIR Detectors

NLIR_D2250_MIR_Detector     MID-Infrared Light 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
  • DC - 10 GHz bandwith
  • NEP down to 2fW/√Hz
  • 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 303.8 KB