Gas analysis using IR light sources Gas analysis using IR light sources

Gas analysis using infrared (IR) light sources

Performing gas analysis by infrared absorption requires a light source to provide energy that will be absorbed by gas molecules. Selecting the proper light source can be a complex process, but Hamamatsu is ready to meet the needs of many applications. From detecting extremely low levels of impurities in clean rooms, to medical capnography, to portable LEL/LFL measurements, we can supply a high performing solution that is also cost effective.

Lineup of light source elements

Gas Analysis Light Source Graph

Infrared (IR) light sources

Hamamatsu has a robust line of MIR light sources for your application of choice.


The quantum cascade laser (QCL) represents a technology revolution, achieving 4+ micron light. Distributed feedback (DFB) lasers can provide linewidth resolution that allows parts per trillion accuracy in some cases. These lasers require a great deal of expertise and auxiliary equipment, so in situations where they aren’t desirable, LEDs can be a great alternative. LEDs' reductions in cost and complexity, coupled with long lifetimes, are an excellent combination for instruments that do not require the performance of a QCL.

Light source Wavelength coverage Source bandwidth Sensitivity or detection limit
Quantum cascade lasers 4-10 µm Extremely narrow band Parts per billion (ppb)
Mid-infrared LEDs (RoHS compliant) 3-4.3 µm Some broadband Parts per million (ppm)
Near-infrared LEDs (RoHS compliant) 0.83-1.55 µm Some broadband Parts per million (ppm)

Quantum cascade lasers (QCLs)

QCLs help instruments detect gases such as COx, NOx, SOx, CH4, NH3, and O3 down to ppb levels or measure isotopes of carbon dioxide and methane. When selecting QCLs, consider these characteristics:

  • Peak emission
  • Tuning
  • Output power
  • Operating temperature
  • Operating current
  • Package (TO can/HHL/butterfly)

We offer QCLs in continuous wave (CW HHL package) and pulsed emission types. They feature high output, high-speed response, and high reliability. Customization options include wavelength range or peak emission, output power, operating temperature, and operating current.

Mid-infrared LEDs

When selecting mid-infrared (MIR) LEDs, consider these characteristics:

  • Pulsing
  • Narrow emission spectrum
  • Power
  • Lifetime
  • Cost

Our line of RoHS-compliant mid-infrared LEDs can bring 3+ micron light at a fraction of the cost of a QCL, and achieve parts per million sensitivity with proper calibration. Currently, we offer LEDs for measuring CH4 (3.3 µm), reference (3.9 µm), and CO2 (4.3 µm). They feature high output, high reliability, and low power consumption.

Near-infrared LEDs

When selecting near-infrared (NIR) LEDs, it is important to consider these characteristics:

  • Pulsing
  • Narrow emission spectrum
  • Power
  • Lifetime
  • Cost

We offer many RoHS-compliant near-infrared LEDs with peak emission within 0.83 - 1.55 µm. They feature high output and high reliability, and they consume less power and have a faster response time than NIR-emitting lamps.

Recommended products

Mid-infrared LEDs

Mid-infrared LEDs having high output with peak emission wavelengths of 3.3, 3.9, and 4.3 μm are available in metal or compact ceramic packages. For detection elements, use quantum detectors such as InAsSb photovoltaic detectors.

Quantum cascade lasers are semiconductor lasers that offer peak emission in the mid-IR range (4 μm to 10 μm). They have gained considerable attention as a new light source for mid-IR applications such as molecular gas analysis used in environmental measurement.

Related videos

Infrared product conversations part 2: Quantum cascade laser (QCL)

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