Application:Gas analysis | DFB-CW QCLs

Trace gas sensing with QCLs

A Distributed feedback (DFB) laser has a superior capability of spectral resolution, and it enable to detect a single and separated absorption line of gas phase molecules.


  • High spectral resolution: Selective detection of gas species 
  • Less infringement by ambient gases: No required preprocessing like dehumidification 
  • To measure up to Lambert-Beer law well: High precision measurement  
  • Possible to consist a configuration no mechanical moving part required 
  • In-Situ measurement for process control


TDLAS carry out high throughput gas sensing with outstanding sensitivity

Tunable diode laser absorption spectroscopy (TDLAS) is a spectroscopic technique with semiconductor laser. Saw-tooth current (Ramp wave) injection enables tuning emission wavelength of QCL by the variable feature of DFB laser's emission depending on the operating temperature and injection current level. Also, TDLAS performs high sensitive spectroscopy with lock-in amplifier to detect periodical modulation of lasers.

Configuration of TDLAS

CW controller C16174-01 (semiconductor laser driver)

CW controller C16174-01 is a semiconductor laser driver with ultra-low noise characteristic. C16174-01 is a ideal control unit to carry out TDLAS as it has the capabilities: wavelength modulating function, and TEC (Peltier) controller with 1 mK stability. A theoretical linewidth of DFB QCL is known as narrower than 1 kHz. *1 A low noise power supply is indispensable to embrace this excellent linewidth feature for high precision detection. The linewidth of QCL could be deteriorated to around 300 GHz when you use noisy laser driver, high jitter or high ripple. The combination of low noise driver and DFB QCL is a considerable solution to achieve narrow linewidth and high precision measurement.

Datasheet of CW controller C16174-01


1."Measuring frequency noise and intrinsic linewidth of a room-temperature DFB quantum cascade laser", Opt.  Express, 19, 179996 (2011)

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