Research Of CO₂Laser MOPA System

Through many year’s research and study, it is now the common knowledge that LPPis the best way to produce high quality,115W EUV light sourse for the next generationlithography. LPP is the abbreviation for laser produced plasma, which means using laser toshot at targets to generate plasma. And to generate more plasma, it requires laser with veryhigh energy intensity and very good beam quality. So, the acquirment of such laser beam isone of the most key problem in the manufacture of next generation lithography system. Byusing the technology called MOPA, which means inject small energy laser into an amplifierto increase its power, theoretically one can get the high energy laser with the good beamquality that required in LPP.This thesis foucs on the energy amplification of the CO2laser MOPA system. Itmainly contains two parts: theoretical Work and pratical Work, as they followed.(1) theoretical: Performed a theoretical simulation on how the average energy of cwand pulsed laser would be amplified using the Frantz-Nodvik equation. Performed asimulation on the wave form change of the pulsed laser during the amplification by usingthe four temperature model；(1) Pratical:Gived a minute introduction about the CO2laser MOPA system we built,Explained the system’s instruction and its ability to amplify the laser energy. Analized thefactor that had great impact on laser energy amplification such as coupling, loss, and so on.And provide solutions to improve the output power.