| Lasers operating at900 nm has been used in vapor detection,ozone detection and differential absorption radar,among which vapor detection and under water communication requires lasers with high repetition rate and high peak power.946 nm laser could be achieved by the quasi-three-level transition of Nd3+ions(4F3/2→4I9/2).In addition,473 nm laser could be achieved by frequency-doubling technology.Such laser has been applied in biomedicines,high density optical data storage and digital video technology.Therefore,the study of 946 nm pulse laser is essential.In the thesis,characterization of transition metal dichalcogenides have been studied.The WSe2 nanosheets were characterized by Raman spectrum,Atomic force microscopy and linear transmittance experiments.The WSe2 used in the experiment has been proved to be monolayer.The nonlinear optical properties have also been studied by Z-scan measurement,and the relevant parameters are obtained.Double Q-switching operation has been used in the study to obtain 946 nm pulsed laser with high peak power,short pulse duration and high quality.The WSe2 nanosheets could be used as saturable absorber due to its saturable absorption property and thus been applied in the resonator for passive Q-switching operation.An electro-optical crystal MgO:LiNbO3 cut for double Brewster’s angle was applied to actively modulate the laser for polarized pulses output.The laser was side-pumped by a laser diode array.A synchronous signal generator was employed to ensure the LD arrays and the MgO:LiNbO3 modulator being triggered synchronously.Output properties including power,pulse duration and single pulse energy of such double Q-switched laser has been studied.In addition,Q-switching operations have been theoretically explained by the rate equations,and the experimental results were in good agreement with the simulation results. |
