Research on high-power DFB laser chips for laser photoacoustic spectroscopy

Laser photoacoustic spectroscopy is a detection technology for trace gas based on photoacoustic effect, which has important applications in monitoring the concentration of dissolved gas in transformer oil. The laser photoacoustic spectrum measuring device mainly includes a light source (laser), a photoacoustic pool, a sound sensor and a signal processing unit, in which the light source provides a long-term stable working narrow band laser for the measuring device, which is an important part. Among many laser sources, high-power DFB semiconductor lasers gradually replace other light sources with their advantages of miniaturization, high reliability, precise wavelength, and low cost. The higher the laser power, the higher the detection sensitivity. For the concentration monitoring of dissolved gas in transformer oil, this paper developed a high-power DFB laser with different characteristic gases corresponding to the absorption wavelength based on indium phosphide substrate material. The wavelength of DFB laser ranges from 1532nm to 1683nm, and the power output of more than 60mW can be achieved in this range. At the same time, the vertical divergence Angle of the laser is reduced through the waveguide extension layer, and the coupling efficiency of the laser is increased when it is packaged into devices.