210~250 nm可调谐窄线宽钛宝石激光器

210~250 nm Tunable Narrow Linewidth Ti:Sapphire Laser

210~250 nm的紫外波段(K波段)是分析物质分子结构的重要波段,包含2个共轭双键的分子在这一谱段内具有较强的吸收峰。为实现这一波段激光信号连续可调谐高功率输出,以TEM_(00)模Nd:YLF 527 nm激光作为泵浦源,采用光栅选频的直腔结构,实现了钛宝石激光连续可调谐输出。通过二倍频、四倍频,实现了210~250 nm的紫外激光输出,在220 nm处得到最大稳定输出功率85 mW,在230 nm处获得四倍频最大转换效率33.3%,是进行紫外吸收光谱分析的优质光源。

All-solid Ti:Sapphire tunable laser at 210~250 nm is of great importance in laser processing,laser etching,biomedicine and spectroscopy.Especially,it has good advantages in spectroscopy.In the field of Raman spectroscopy,the excitation efficiency of ultraviolet lasers is much higher than visible light.In the field of the K-band of ultraviolet absorption spectroscopy,210~250 nm is an important band for analyzing the molecular structure of substances.For example,molecules containing two conjugated double bonds can be detected when the strong absorption peaks occur.These require that the tunable band of Ti:Sapphire laser is converted to the ultraviolet band through nonlinear optical frequency doubling technology.Moreover,the ultraviolet tunable lasers should have the advantages of good stability,wide tunable range,good beam quality,high laser signal energy,and good directivity.To meet the above application requirements,the research of all-solid Ti:Sapphire tunable laser at 210~250 nm is demonstrated.Based on the principle of Ti:Sapphire tunable laser,the characteristic of the Ti:Sapphire crystal is learned.Given the rate equation,the interation between Nd:YLF 527 nm pump source and Ti:Sapphire crystal is studied.Besides,it is studied that the principle of frequency doubling output of Ti:Sapphire fundamental frequency from infrared to ultraviolet.Moreover,the design index and overall scheme of the Ti:Sapphire ultraviolet tunable laser is given.The key technology of TEM_(00) mode Nd:YLF 527 nm laser is studied.Firstly,the basic principle of Nd:YLF higher-power laser based on MOPA technology is studied.Secondly,the schematic of 527 nm pump source laser based on MOPA technology is studied and the pump laser is developed.Finally,the output characteristics of the 527 nm laser is analyzed.The design method of Ti:sapphire fundamental frequency cavity is studied.Based on the method,a fundamental frequency cavity based on the straight cavity structure using grating selection frequency is designed.Furthermore,the techniques of tuning and narrow linewidth compression are researched.Last,the nonlinear frequency doubling technology,phase matching principle,and factors affecting frequency doubling conversion efficiency is deeply researched.Given the theory above,the crystals of second-harmonic generation and crystals of fourth-harmonic generation are selected and designed.A Ti:Sapphire tunable laser system is developed,and the output characteristic parameters are collected and analyzed.System obtains the fundamental frequency laser of 760~1000 nm,and obtains the maximum fundamental frequency power of 912 mW at 820 nm.The second harmonic generation of 420~500 nm is obtained using LBO crystal,and the maximum power of 380 mW is obtained at 440 nm.Then,the fourth harmonic generation of 210~250 nm is obtained using BBO crystal.Maxi-mum conversion efficiency of fourth harmonic generation is achieved with 33.3%at 230 nm.At 220 nm,the stable output of up to 85 mW is obtained,and its fluctuation does not exceed 1.5%within 120 minutes.