Research Of External Cavity Semiconductor Laser

Semiconductor laser with characteristics of narrow line width,tunableness andstable frequency is the necessary source of WDM,DWDM and coherent lightcommunication, it is also widely used in high frequency laser spectrum,detectionand measurement,fiber sensor etc. The most effective and convenient way tonarrowing line width and improving output spectrum is using external cavity toselect modes on the base of common laser which is also the emphasis in this paper.At first, the development and applications of external cavity semiconductor laserfrom its putting forward to today was introduced, then, expatiated on coupleresonator theory,mode selection theory,temperature and modulation characteristics.In addition, several important parameters such as threshold gain,output power,linewidth and side mode rejection ratio were emulated and calculated with Matlab andthe results were a close match for theory deduces. Besides this, the paper alsoresearched the tune process of external cavity semiconductor laser, discussed severalcircuit designs in detail which can realize automatic control of stepping motorthrough micro-controller in order to change the length of external cavity. Due tosome processes can be realized on LPC2104EasyArm board which is fit for learnerof Arm and embedded system very much, thus, the applications of this board are alsointroduced. All of the calculation results and deduce processes in this paper areanalyzed too, summarized the achievements and deficiencies. The paper has somereference value in research of external cavity semiconductor laser.