Research On All Solid-state Pulsed Laser Based On Two-dimensional Material Absorber

All-solid-state short-pulse lasers have the advantages of low price,stable output pulse,narrow pulse width,high repetition frequency,high energy,etc.Therefore,it has a great role in many fields such as precision processing,laser medical treatment,scientific research,and national defense military.At present,Q-switching and mode locking are the main technical means for obtaining short pulses,and the output of saturable absorbers determines the pulse output results.Recently,a new type of two-dimensional material has emerged as a saturable absorber for using in solid-state lasers.Compared with traditional saturable absorbers,it has wider bandwidth,lower price,and easier maintenance,so it has received extensive attention.The new two-dimensional material expands the types of saturable absorbers and optimizes the performance of all-solid-state short-pulse lasers.Based on this,this article uses molybdenum disulfide and graphene oxide as saturable absorbers and applies them to solid-state lasers.The main work contents and innovations are as follows:First,briefly introduce the physics and optical properties of the Nd:YAG crystal used in the experiment,and the way in which a solid-state laser acquires a short pulse is described.In addition,the thermal lens effect of the crystal is theoretically analyzed.In consideration of the focal length of the thermal lens,a Z-cavity is designed using the ABCD matrix to provide guidance for the cavity design for subsequent experiments.Secondly,using a method of electron beam evaporation,a metal silver film having a thickness of about 195 nm is plated on the quartz plate.By measurement,the silver mirror has a reflectance of 89%at a wavelength of 1064nm.Next,the solution prepared by the liquid phase lift-off method was attached to the surface of the silver mirror substrate by a droplet method to obtain a reflection-type saturable absorber having a modulation depth of 3.05%.Again,using the reflective absorber prepared above,insert into an improved five-mirror W-shaped folded cavity to obtain a Q-switched mode pulse with a maximum output power of 1.06W.The Q-switched pulse width is approximately 5?s and the repetition rate is 33.9kHz.The single-pulse energy of the Q-switched pulse is 31.2?J and the peak power is 6.24W.In the Q-switched envelope,a mode-locked pulse with a repetition frequency of 94.72 MHz is obtained.Third,a graphene oxide saturable absorber was prepared by a liquid phase lift-off method and was reduced using a thermal reduction method.Through a variety of characterization methods,the presence of reduced graphene oxide was confirmed.Secondly,the graphene oxide and graphene oxide were fabricated into saturable absorbers to complete Q-switching experiments in solid-state lasers.When graphene oxide was used as the saturable absorber,the average output power was 1.41 W,and the pulse width was 328ns,the repetition rate is 854kHz,the single pulse energy is 1.65?J,and the peak power is 5W.When using reduced graphene oxide as the saturable absorber,the Q-switched pulse output power is 1.61W,the pulse width is 360ns,and the repetition frequency is 800kHz,single pulse energy is 2.O?J,peak power is 5.7W.