Study Of The Novel Fiber Laser Based On Nonlinear Polarization Rotation Technique And Franckeite Saturable Absorber

Pulsed fiber lasers are indispensable in many sectors such as material micromachining,fiber optic communication,medical treatment and precision measurement.Nonlinear polarization rotation technology is a common way to realize pulsed laser output,with the superiorities of simple construction,wide range of applications,high damage threshold,both for industrial production and basic research is of excellent significance.In addition,the formation of pulsed laser output on fiber lasers by virtue of the saturable absorption properties of two-dimensional(2D)materials is also an international research hotspot.The search for new and efficient 2D materials has been the direction of researchers’efforts.The superiorities of franckeite,a new 2D material,can be specifically attributed to its high stability in natural environment,easy preparation,ultrafast response and narrow band gap,which reveals its potential in the field of ultrafast optical devices.In this thesis,firstly,the characterization of the Nd-doped fiber laser based on nonlinear polarization rotation is carried out;And secondly,franckeite is applied to the field of fiber laser and its optical properties are experimentally investigated.The main research contents of this thesis are as follows:1.Many influencing factors involving pulse transmission such as loss,dispersion,nonlinearity,etc.are analyzed,based on which transmission equations are established and numerical simulations are performed to provide a theoretical basis for the formation and interpretation of soliton pulses in subsequent experiments.2.For the first time,based on the nonlinear polarization rotation regime,the output of noise-like pulses was realized with a self-built neodymium-doped mode-locked fiber laser as the platform.The pulse center wavelength,3 dB bandwidth,and heavy frequency are 1063.75 nm,2.27 nm,and 14.25 MHz,respectively,at a pump power of 300 mW,and the pulse width reaches the order of picosecond.3.The monolayer of franckeite was obtained by liquid-phase exfoliation,and the saturable absorber with sandwich structure was obtained by using polyvinyl alcohol to form a thin film,and a series of metrologies on its optical properties were carried out,and the events of the explore confirmed that franckeite has the ability to be an excellent saturated absorber material.4.For the first time,the relevance between franckeite and pulse narrowing was substantiated.Firstly,the mode-locking regime was probed with a self-built ytterbium-doped fiber laser as the experimental platform,and a mode-locked pulse with a repetition frequency of 1.767 MHz and a maximum output power of 9.42 mW with a high signal-to-noise ratio was captured.Secondly,the Q-switched pulse output was attained on the erbium-doped fiber laser,and the average output power raised from 0.1 mW to 1.2 mW and the pulse repetition frequency climbed from 47.04 kHz to 71.91 kHz as the pump power climbed from 260 mW to 530 mW.