Research On Passive Q-switched Laser Based On A Novel Saturable Absorber

Q-switched pulsed lasers have the advantages of high peak power,large pulse energy,and stability,and can be commonly used in industrial processing,military,and communications.In recent years,passively Q-switched pulsed lasers based on new low-dimensional nano-material saturable absorbers have attracted attention because of their advantages such as simple cavity type,high damage threshold,and high output power.In this paper,we mainly study Q-switched pulsed lasers based on MoS₂,black phosphorus and Cu_2-x-x Se@Cu_2-x-x S saturable absorbers,and study their pulse characteristics.The main research content is as follows:（1）A MoS₂/PVA saturable absorber was prepared.The depth of formation of MoS₂/PVA was 30.4%,and the saturation light intensity was 14 MW/cm².Based on MoS₂,passive Q-switched nanosecond pulse output is realized in Yb-doped fiber lasers with a center wavelength of 1063.25nm and a spectral line width of 0.1nm.When the pump power reaches220m W,the pulse width is 22.8ns and the repetition rate is 2.71 MHz.The power is 4.53nJ and the output power is 9.84mW（2）Prepare a BP/PMMA saturable absorber with a modulation depth of 12.1%and a saturated light intensity of 9.08 MW/cm².Based on BP saturable absorbers,passively Q-switched nanosecond pulsed output is achieved in Er-doped fiber lasers.When the pump power is 220m W,the pulse width is 530ns,the repetition rate is 186.8 kHz,the single pulse energy is 347nJ,and the output power reaches 65mW..（3）A self-doped semiconductor nanocrystalline Cu_2-x-x Se@Cu_2-x-x S/PMMA saturable absorber was prepared with a modulation depth of 25%and a saturated light intensity of 3.97mJ/cm².Through the pump detection technology,a significant plasmon resonance absorption at the center wavelength of 1030nm is obtained,the fast decay time constant is 0.495 ps,and the slow decay time constant is 51.4ps.Based on Cu_2-x-x Se@Cu_2-x-x S saturable absorbers,passive Q-switched microsecond pulse output is realized in Yb³⁺:YAG-doped solid-state lasers.When the pump power is 8.7W,the pulse width is 8.5μs and the repetition frequency is 45.45KHz.The single pulse energy reaches 4.11μJ and the output power is 187mW.