Research On 2?m Pulsed Laser Based On New Two-dimensional Materials And Mode-Locked Narrow Line-width Light Source

Pulsed fiber lasers have the advantages of large pulse energy,high peak power,high efficiency,and compact structure.They have broad application prospects in many fields such as laser communication,production processing,and biomedical.As a human eye safety laser,the 2?m pulsed fiber laser has been widely concerned,and the pulsed fiber laser based on new two-dimensional materials has become a research focus due to its unique advantages.This article focuses on 2?m passive Q-switched fiber lasers based on antimonene?Sb?saturable absorbers?SA?,2?m passive mode-locked fiber lasers based on lead sulfide?PbS?saturable absorbers,and Raman fiber laser with 2?m narrow line-width mode-locked source as seed source.The specific content is as follows:The transmission equations of pulses in single-mode fiber and gain fiber are derived,the mathematical model of saturable absorber is established,and the numerical model of passive mode-locked fiber laser is established.The simulation analysis is beneficial to the saturable absorption parameters of mode-locked pulse.The self-made thulium-doped(Tm³⁺)mode-locked fiber laser amplifier was used to measure the non-linear absorption characteristics of Sb-SA at 2?m.The modulation depth,unsaturated loss and saturation intensity were 10.66%,64.12%,and 8.77GW/cm².Based on Sb-SA passive fiber laser,the center wavelength is 1961.8 nm,the repetition frequency range is 24.75⁶0.97 kHz,the minimum pulse width and maximum pulse energy are 2.44?s and 200 nJ,and the signal-to-noise ratio?SNR?is 52.2 dB.This is the first time that Sb-SA is used to achieve Q-switched pulse at 2?m,which indicates that Sb-SA has potential Q-switched performance at 2?m.Measure the saturable absorption characteristics of PbS-SA at 2?m,and build a passive fiber laser based on PbS-SA to achieve stable fundamental and second-order mode-locked pulses.The center wavelength of the fundamental-mode-locked pulse is1957.37 nm,the 3-dB is 3.43 nm,the pulse width and repetition rate are 1.24 ps and21.93 MHz respectively;the center wavelength of the second-order mode-locked pulse is 1961.2 nm,3-dB is 4.22 nm,the pulse width is 1.09 ps,and the repetition rate is43.86 MHz.This is the first time that PbS-SA is used to achieve mode-locked pulses at2?m,which provides a new way for 2?m to generate mode-locked pulses using saturable absorbers.A narrow-band reflection grating with a bandwidth of 5 nm is added to the mixed mode-locked cavity composed of a nonlinear polarization rotating structure and a saturable absorber of carbon nanotubes to compress the line width,and a narrow line with a center wavelength of 1977 nm and a line width of 0.08 nm is obtained The wide light source is used as the seed source.The seed source amplifies the seed power through the two-stage MOPA amplification system as the pump source of the Raman laser.The pump light generates a two-order Raman laser output based on the Raman effect of the UHNA7 high-nonlinear fiber.The second-order Raman laser is at 2160 nm,and the second-order Raman laser is at 2374 nm.