Research On Linearization Chirp Technique Of DFB Semiconductorlaser

Linear Frequency Modulated Continuous Wave(LFMCW) is a non-contact, automatic and precise absolute range measuring technology which is notable for its high efficiency as well as its lack of measuring blank area. It’s based on the linear frequency modulating of the laser. But it’s not so convenient for few linear frequency modulated laser were there in reality, which leads to a broaden of the beat signal and results a bad accuracy and resolution.This chapter deals with the cause and effects of the non-linearity of the frequency of the laser based on a DFB laser. A frequency modulating property testing system of a DFB laser was designed and constructed, as well as a pre-reviseof the non-linearity and a closed-loop rectify system of the non-linearity based on the feedback of light and electrical. Much experiment was done together with enough analysis.Learning the basis of range measuring of linear frequency continuous wave, we analyzed the impact on accuracy and resolution of the measuring caused by non-linearity of the laser, and talked about the generation of non-linearity of the DFB laser.A prototype of the revise of DFB laser was concluded,as well as an according system. This works well for it reduced the non-linearity on a large scale. Also,this method can also be applied to other types of current injection.A thorough analysis of the theory of non-linearity revise of DFB laser was done by an equivalence to a classical electrical phase-lock loop。At last,a comparison of the repeatability of the range measuring between revise and non-revise of non-linearity was done,which testified that the method of revise work well for its efficiency on reducing non-linearity of the laser,which at last prompt the accuracy of repeatability on measuring. But the inevitable noise in the system,the fluctuation of the power and the inflection point effect all affect the consequence of the revise. If these impact could be eliminated, we can see a better result.