Investigation On Er³⁺-doped Pulse Fiber Laser Based On Novel Transition Metal Dichalcogenides

The great application pulsed fiber laser has a wide operating wavelength range from near infrared to mid-infrared with its rare earth ions in gain medium.And it is widely used in optical fiber communication,laser processing,biomedicine and other fields due to its excellent beam quality,simple structure,low cost and the ability to withstand high power.In this paper,a new type of Q-switched and mode-locking fiber laser based on two-dimensional material to generate short pulses is explored.The research work of this paper are listed below:1.An Er³⁺-doped Mode-Locking all-fiber laser based on nonlinear polarization rotation effect is constructed.The stable soliton pulse output with a minimum pulse width of 254 fs is obtained,and its repetition rate is 37.83 MHz.The central wavelength of the output pulse is 1563 nm,the spectral width is 9.78 nm,and the maximum average output power is 38.6 mW.This oscillator is used to measure the optical properties of the saturable absorber in next chapters.2.We built a Mo_0.5W_0.5S₂-PVA based Er³⁺-doped Q-switched all fiber laser at the first time,The output pulse with the shortest pulse width of 1.92?s and the maximum single pulse energy of 246.5 nJ was obtained.The modulation depth of Mo_0.5W_0.5S₂-PVA is 15%and the saturation strength is 13.97 MW/cm².The repetition frequency of the output pulse increases from 52 kHz to 118.4 kHz with the increase of pump power.The maximum output power is 26.9 mW when the pump power is 600 mW.3.We built a fiber tapered Mo_0.5W_0.5S₂ based Er³⁺-doped Q-switched all fiber laser at the first time,.The stable Q-switching operation is achieved in the cavity when the pump power is 140 mW.The central wavelength of the output pulse is 1555.55 nm,and the dual-wavelength operation is achieved when the pump power is high.The shortest pulse width is 1.42?s,and the repetition frequency range is 34.1 kHz-98.5kHz.The maximum output power can reach 15.6 mW,corresponding to the maximum single pulse energy of 172.9 nJ.4.We measured the nonlinear optical properties of anisotropic ternary transition metal sulfide ReS_1.02Se_0.98 alloy.The modulation depth was 1.8%,and the saturation strength was 0.046 MW/cm².It has been applied to the bait-doped fiber laser to realize Q-switching operation near the central wavelength of 1531 nm for the first time,.The pulse width decrease from 4.802?s to 1.07?s,and the shortest pulse width is 1.07?s.The repetition frequency of the output pulse ranges from 75.37 kHz to 152.7 kHz,and the corresponding maximum output power and single pulse energy are 4.32 mW and 28.29 nJ,respectively.In addition,the effects of material anisotropy on Q-switched pulse repetition frequency,central wavelength and output power are also studied.5.The ReS_1.02Se_0.98 saturable absorber is applied to Er³⁺-doped fiber laser.By optimizing the parameters of cavity and components,the mode-locked pulse with a pulse width of 888 fs is obtained for the first time.The central wavelength is 1561.15 nm,the spectral width is 4.85 nm,and the pulse repetition frequency is 2.95 MHz.