Research Based On FePSe₃ Ultrashort Pulse Technology

Pulsed fiber laser has been widely concerned because of its low cost,high conversion efficiency and excellent compatibility.Using the intensity-modulation ability of saturable absorber in fiber laser is an important method to realize pulse.At present,semiconductor saturable absorber is widely used in fiber laser.But it has the disadvantages of high cost,small adjustable bandwidth and easy to be damaged.In recent years,a large number of low dimensional materials with simple fabrication process,low cost and high performance have attracted researcher's attention because of its excellent optical-intensity modulation ability.However,it is still a challenge to find a saturable absorber with strong modulation ability and stable working ability.FePSe3 belong to 2D metal phosphorus trichalcogenides,which has twodimensional layered structure.Its loose layered structure provides the possibility for it to be used as a catalyst,and FePSe3 shows intrinsic antiferromagnetism from bulk to monolayer,so it is also a good choice for studying two-dimensional ferromagnetic materials.In addition,FePSe3 has relatively high electron mobility,which makes it have great potential in the field of optoelectronics.However,there are few reports on the optical properties of FePSe3.In this work,we focus on the preparation,characterization,measurement of nonlinear absorption characteristics,and the influence on the output of fiber laser.the main contents are as follows:1.In the first part of this work,the fabrication,measurement and principle of saturable absorber are analyzed.Firstly,the preparation of low dimensional materials,the principle of characterization,the purpose of testing and the relationship between them are introduced.Then,the characteristics of several saturable absorber carriers are introduced,and the principle and influence of saturable absorber on fiber laser are analyzed from the point of simulation.Finally,the measurement methods of saturable absorption characteristics are introduced.2.In the second part of this work,FePSe3 was prepared by template method of inorganic salt,and it was observed by means of electron transmission microscope and UV-Vis absorption spectrum.After that,it was mixed with acetone solvent by ultrasonic method and vibrated to make a uniform dispersion,and then it was deposited on the tapered fiber by optical deposition method to make an optical intensity modulation device.Finally,the saturation intensity and modulation depth of the device are 312 MW/cm2 and 33.7%respectively.3.In the third part of this work,the output of the pulse laser is realized by applying the saturable absorption device to the fiber laser.The pulses of the fiber laser modulated by FePSe3 saturable absorber include mode-locked pulse,modulated pulse,bright dark pulse and so on.Finally,the differences of these pulses and the reasons of their occurrence are discussed through analysis and comparison.