Research On Frequency Doubling Technology Of High Power Continuous-wave Laser

High power continuous green laser has important applications in laser display,biomedical,non-ferrous metal processing and other fields.The realization of high power and high frequency doubling conversion efficiency continuous green laser output has become a research hotspot in the laser field.In this paper,the end pumped and side pumped Nd: YAG CW solidstate lasers are overlapped,and the frequency doubling characteristics of 1064 nm high-power CW Nd: YAG solid-state lasers are studied and analyzed.A 1064 nm high-power CW fiber laser resonator is constructed by using narrow linewidth fiber grating,and the frequency doubling technology of 1064 nm high-power CW fiber laser is studied.The main research contents are as follows:(1)The pump conversion efficiency and frequency doubling efficiency of end pumped and side pumped Nd: YAG CW solid-state lasers are studied.A 50 W Nd: YAG end pumped Nd: YAG CW solid-state laser and a 43 W 1064nm side pumped Nd: YAG CW solid-state laser are obtained by using 50 W Nd: YAG end pumped Nd: YAG module and side pumped Nd:YAG module respectively According to the experimental results,we can get higher pumping efficiency by side pumping.The experimental results show that the maximum 532 nm green power and conversion efficiency of the end pumped Nd: YAG CW solid-state laser are 1.3 W and 8.9%,respectively,while the maximum green power of the side pumped Nd: YAG CW solid-state laser is 6 W,The conversion efficiency of frequency doubling is13.9%.The frequency doubling efficiency of side pumped Nd: YAG CW solid-state laser is higher than that of side pumped Nd: YAG CW solid-state laser by keeping the two lasers at the same fundamental optical power.Combined with the frequency doubling theory,the experimental results of the two lasers show that the frequency doubling efficiency can be improved only when the phase matching condition is met.(2)In order to further study the frequency doubling characteristics of high-power side pumped Nd: YAG CW solid-state laser,the 50 W side pump module is replaced by a higher power side pump module,so as to improve the fundamental frequency optical power output to 100 W level.That is to say,a 1064 nm side pumped Nd: YAG CW solid-state laser with 105 W fundamental frequency optical power is obtained.The frequency doubling is also carried out by using KTP crystal external frequency doubling,and the 532 nm green output power is25 W,and the conversion efficiency of frequency doubling is more than 20%.Combined with the theoretical analysis and experimental results of frequency doubling,it can be seen that under the condition of phase matching,increasing the fundamental optical power can improve the frequency doubling efficiency of the laser.(3)In order to study the frequency doubling characteristics of high-power CW fiber laser,a 1064 nm CW fiber laser is built experimentally.The resonator is composed of a narrow linewidth grating with an output linewidth of 0.05 nm.The 1064 nm CW fiber laser with an output spectral width of 0.05 nm and an output power of 100.5 W is obtained based on the theory of frequency doubling,the influence of narrow linewidth fundamental frequency light source on the frequency doubling efficiency is analyzed.By setting contrast experiments,it is further confirmed that the fundamental frequency light source can improve the frequency doubling efficiency of laser under the condition of narrow linewidth.(4)In order to further study the frequency doubling characteristics of high-power CW fiber laser,based on the 1064 nm narrow linewidth CW fiber laser,the linearly polarized fundamental frequency source is obtained by polarizing prism and half wave plate.Combined with the frequency doubling theory and experimental results,the frequency doubling conversion efficiency of Yb doped CW fiber laser in narrow linewidth and linearly polarized state is analyzed,and the 1064 nm narrow linewidth CW fiber laser is confirmed Under the condition of on-line polarization,the frequency doubling efficiency can be further improved.(5)This paper summarizes and analyzes the shortcomings of the experimental technical scheme,and puts forward the improvement scheme.