Research On Picosecond Mode-locked Laser And Picosecond Frequency Conversion Based On New Materials

Solid-state lasers are the most widely used and that get the most attention in daily production and life.The wavelength of a solid laser is constant or tunable in a small range,and the actual application needs to broaden the laser band.In this paper,the solid picosecond mode-locked laser and picosecond green laser have carried on the review and summary,the experimental research on the picosecond mode-locked lasers based on new materials and picosecond frequency conversion have been studied,the tungsten disulfide?WS₂?solid mode-locked laser and picosecond green laser are achieved here.The main contents are introduced as follows:The first part described the development of solid picosecond mode-locked laser and picosecond green laser.Then,a brief introduction on the WS₂ solid mode-locked laser was presented.Especially,a brief introduction on the recently developed of K₃B₆O₁₀Br?KBB?and K₃B₆O₁₀C_l?KBOC?crystal frequency doubling of green laser was explained.Secondly,the basic theory of the experiment was investigated,including the basic principle of the mode locking and the frequency conversion.In the mode locking theory,the basic principle and several methods of realizing mode-locked were introduced.In the theory of frequency conversion,the basic principle of the second harmonic,the factors influencing frequency doubling and the characteristics of nonlinear optical crystals were presented.The third part gave an overview on the experiment of the new material based picosecond mode locked laser.At first,passively mode locked Nd:LuVO₄picoseconds laser based on the WS₂ saturable absorber was studied.Then,we demonstrated a passively picosecond mode-locked Nd:LuVO₄ laser with WS₂ as the saturable absorber.When the pump power was 3.3 W,the maximum output power was 1.18 W with optical conversion efficiency of 36%.The mode-locked pulse interval is about 12.5 ns,with a repetition rate of 80 MHz,which was consistent with the theoretical calculation.The pulse energy of mode-locked laser was calculated to be 14.8 nJ.The experiment obtained the output of picosecond green light successfully.However,the mode-locked laser pulse was not very stable,so the pulse width of the mode-locked laser was not measured.Finally,we demonstrated a green light laser based on KBB and KBOC crystal.On the one hand,the green picosecond laser was studied through intracavity frequency doubling and external frequency doubling.It was based on a type I phase-matched KBB crystal.The average output power was 185.00 mW of green picosecond laser through intracavity frequency doubling experiment.The average output power was 3.00 W of green picosecond laser with the maximum frequency was39.7%through external frequency doubling.The experimental results show that KBB crystal is a promising nonlinear optical crystal.On the other hand,a type I phase-matched KBOC crystal was selected for frequency doubling to obtain the green light.The output power of green light was 1.21 W when the pump power of 1064 nm was 7.38 W with a repetition frequency of 10 kHz.While for a 10 Hz ps laser,the output pulse energy at 532 nm was 1.78 mJ per pulse,with an optical conversion efficiency of 36.0%.