基于窄线宽光栅的光纤激光器倍频技术

Frequency Doubling of Fiber Laser Based on Narrow Linewidth Grating

高功率连续绿光激光器在激光显示、生物医疗、有色金属加工等领域有着重要的应用,该研究课题已经成为激光领域的研究热点。为了实现高功率、高效率连续绿光激光的输出,利用窄带光纤光栅搭建了高功率光纤激光器,并以此为基频光源进行倍频技术的研究,得到了带宽小于50 pm的基频光纤激光器,输出功率可达100 W。利用该基频激光以腔外单程方式倍频KTP晶体,实现了11.6 W的532 nm绿光输出,倍频效率为11.6%;利用偏振棱镜将该基频光起偏后得到线偏振光,对透过偏振棱镜的p偏振光进行倍频实验,得到532 nm倍频光的输出功率可达7.3 W,倍频效率为14.2%。以上实验证明利用窄线宽光栅来控制基频光源的光谱带宽,可提高光纤激光器的倍频效率,若将经偏振棱镜分光后被反射出去的s偏振光进行倍频,可得到532 nm绿光,利用合束技术将两束绿光进行合束,有望将绿光功率提高至14 W以上。

High power continuous green lasers have important applications in laser displaying,biomedicine,nonferrous metal processing,and other fields.These research issues have become hot topics in the laser field.Therefore,to achieve high power and high efficiency continuous green laser output,a high-power fiber laser is built by using a narrow-band fiber grating,and the frequency doubling technology is studied by using the laser as the fundamental laser source.The fundamental frequency fiber laser with a bandwidth less than 50 pm is obtained,and the output power can reach 100 W.Based on this fundamental frequency laser,532 nm green laser output of 11.6 W is achieved by using a one-way frequency doubling KTP crystal,and the frequency doubling efficiency is 11.6%.Linearly polarized laser is obtained by polarizing the fundamental frequency laser with a polarizing prism.The frequency doubling experiment of p-polarized laser passing through a polarizing prism is carried out.The output power of 532 nm frequency doubling laser is 7.3 W and the frequency doubling efficiency is 14.2%.These experiments show that the frequency doubling efficiency of fiber lasers can be improved by controlling the spectral bandwidth of fundamental frequency laser via the narrow linewidth grating.The 532 nm green laser can be obtained by doubling the frequency of the s-polarized laser reflected by the polarizing prism.The green laser power can be increased to more than 14 W by combining two green laser beams via the laser beam combination technology.