Preparation Of Two-dimensional Saturable Absorbers And Their Application In Solid-state Q-switched Lasers

Short pulse solid-state laser has a broad application prospect in the field of practical science and technology such as laser ranging,laser processing and laser medical treatment because of its advantages of stability and durability,high pulse energy and excitation wavelength.The saturable absorber nonlinear modulator is the core of the short pulse passive Q-Switched solid state laser.Stable saturable absorber is an important link that restricts the development of short pulse lasers.Therefore,it has become a hot topic to explore the materials and preparation methods of saturable absorber with excellent performance.In this paper,the saturable absorbent of CH3NH3PbI3 perovskite film and the saturable absorbent of sol-gel molybdenum disulfide film with high damage threshold were prepared by spin coating method.The saturable absorbent(SA)of graphene oxide(GO),molybdenum disulfide(MoS2)and tungsten disulfide(WS2)film were prepared by Langmuir-Blodgett(LB)method respectively.The saturable absorber of molybdenum carbide(Mo2C)film was prepared by magnetron sputtering.The characterization and optical properties of the saturable absorbers were studied.Finally,they are respectively applied to the Nd-doped solid-state laser to achieve a stable Q-Switched pulse output.The research contents of this paper include three aspects:1.Two CH3NH3PbI3 perovskite film SA by the method of spin coating was prepared,and applied to the Nd:YAG and Nd:YVO4 solid-state laser,respectively.The stability of the passive Q-Switched pulse output was achieved in the central wavelength of 1.06 μm and 1.34μm.It is show that CH3NH3Pb13 perovskite film materials can be used as a kind of excellent SA and its application in solid state laser.The high damage threshold of MoS2-doped glass-composite absorber was synthesized using the sol-gel method and spin-coating technique.After inserting MoS2/SiO2-SA into a linear Nd:YAG laser cavity,a stable passively Q-switched laser with a maximum average output power of 3.22W was obtained.Overall,our results demonstrate the strong potential that nonlinear optical material-doped sol-gel glass SAs have for high-power laser applications.2.A new method of preparing SA films of two-dimensional nanomaterials on different substrates was fabricated using LB method.The SA exhibited more excellent uniformity,larger nonlinear performance,controllable thickness and good repeatability at room temperature and pressure.Herein,the SA of three different materials was obtained by LB method.Firstly,two kinds of GO films on the quartz substrate under the 22 and 38 mN/m surface pressure were fabricated using the LB method and applied them into a passively Q-Switched Nd:YAG laser operated at 1064 nm.The maximum average output power of this laser was 1.313 W and the corresponding pulse duration was 156 ns.Secondly,a compact reflective MoS2-SA was fabricated by coating a few layers of a MoS2 thin film on a silver mirror using the LB method.By useing the LB MoS2-SA into a V-shaped Nd:GdVO4 laser cavity,a stable Q-switched laser operation with the maximum average output power of 0.89 W corresponding to a pulse width of 91.6 ns is obtained.Thirdly,a WS2 film SA on a high transmittance quartz substrate was fabricated by LB method.By inserting it into the Nd:GdVO4 linear laser cavity,stable Q-Switched laser was obtained.The maximum average output power was 811 mW and the minimum pulse duration was 337 ns.The experimental results fully demonstrate the application potential of the saturated absorber prepared by LB method in solid-state pulse lasers.3.Two kinds of film saturable absorbers,transmission type and reflection type,were prepared on quartz substrate and reflector by magnetron sputtering respectively.The transmittance absorption was obtained by sputtering high purity molybdenum carbide material on a quartz substrate with high transmittance by magnetron sputtering,and showed good nonlinear saturation absorption characteristics at 1.06 μm and 1.34 μm,and the modulation depth was 10.39%and 8.89%,respectively.It was used to Nd:YAG and Nd:YVO4 linear laser cavities,respectively,a stable Q-switched laser operation at 1064 nm with the maximum average output power of 547 mW corresponding to a pulse width of 136 ns was obtained.In addition,the usage of 2D Mo2C-SA in Nd:YVO4 solid-state lasers to generate short Q-switched pulses at 1.34μm with good long-term stability was demonstrated.The maximum average output power of 236 mW and pulse width of 222 ns was obtained.Reflective type MXene Mo2C thin films were fabricated on a silver mirror by the magnetron sputtering method and it was used in passively Q-switched solid-state pulsed laser generation at the central wavelengths of 1.06 and 1.34 μm,respectively.By inserting the Mo2C SAs into V-shaped Nd:YAG,the short pulses were generated with the pulse duration and average output power of 254 ns and 275 mW respectively at 1.06 μm.In addition,the usage of 2D Mo2C SA in Nd:YVO4 solid-state lasers at 1342 mm was demonstrated.The maximum average output power was 293 mW,the pulse width was 313 ns.The results show that the film SA with uniform surface can be obtained by magnetron sputtering.As a SA,Mo2C 2D has a great application prospect in solid state lasers.