Development of 1650nm DFB lasers applied in trace methane detection

Optical absorption method is effective for trace methane detection and is extensively used in foul gas measurement and alarm in case of coal mining tunnel.In order to obtain a monochromatic light source for detecting the methane absorption at 1653nm wavelength,a 1653nm distributed feedback(DFB)laser was obtained from multi quantum well material design and epitaxy to device package with technologies such as metal-organic chemical vapor deposition epitaxy and nanoimprint lithography. The laser demonstrated 52dB side mode suppression ratio,14.9% external quantum efficiency,no more than 12mA threshold current,0.11nm@ 20dB line width matching the absorption band of methane at 1653nm,and stable optical and electrical characteristics.Less than 1.3% error was obtained for detection of methane with gas volume fraction from 0.005 to 0.05,based on the DFB laser.The result shows that the device is suitable for trace methane detection in engineering by means of harmonic detection and can be manufactured in mass production.