Different gas molecule has different absorption spectrum due to different characteristic structure

spectrum absorption gas sensor is produced by absorption of specific wavelength.In spectrum absorption gas concentration detecting system

it is important to ensure stability of output wavelength exported by semiconductor laser

and temperature of laser is one of the major factors affecting wavelength.At present

thermistor inside laser is used to measure temperature of laser

but the structure of thermistor confines measurement can not to be accurate and fast

so the detection is not able to work well.To solve this problem

through analysis on application of vertical cavosurface launching semiconductor laser

on the basis of previous thermistor

monitoring of the wavelength exported by laser is added.So the temperature control scheme based on double detection of thermisor and output wavelength is proposed

and the traditional temperature control scheme only depends on one-parameter of thermisor is changed

at last the digital PID control of two parameters is formed.Experimental results show that the temperature deviation can be controlled at 0.01 ℃

and the working stability of optical gas sensor is improved.