| Recently,ultra-short pulse all-fiber lasers have been widely used in various fields such as material processing,optical devices,optical communications,fiber optic sensors,lidar,microscopy,and biomedicine due to their simple and compact structure,high stability,and relatively low production cost.Pulse laser output is mainly achieved through techniques such as nonlinear polarization rotation(NPR),nonlinear amplifying loop mirror(NALM/NOLM),and saturable absorbers(SA).Compared to NPR and NALM techniques,fiber lasers based on real SA have lower sensitivity to the environment and are more conducive to the commercialization of fiber lasers.In recent years,various two-dimensional materials have emerged,such as graphene,single-walled carbon nanotubes(SWCNTs),semiconductor saturable absorber mirrors(SESAMs),black phosphorus(BP),topological insulators(TIs),transition metal dichalcogenides(TMDs),and layered metal sulfides(LMSs).These materials,with their excellent optical and electronic properties,have been widely used as SAs to achieve pulse laser output in fiber or solid-state lasers.Antimony trisulfide(Sb2S3),as a novel layered metal sulfide,possesses excellent optoelectronic and optical properties.It exhibits good saturable absorption characteristics in the range of 0.9-1.6μm,making it suitable as a saturable absorber in fiber lasers.It can not only achieve pulse laser output but also serve as an effective research platform for observing,exploring,and studying the formation mechanism and dynamic evolution of soliton pulses.It has both practical application value and theoretical research value.The main contents of the paper are as follows:1)Sb2S3 nanosheets were successfully prepared using a liquid-phase exfoliation method.Optical films with excellent optical properties were fabricated using polyvinyl alcohol(PVA)as a matrix,and they were futher used to create fiber-compatible SA through a sandwich structure.Microstructure and optical property observations and characterizations of Sb2S3 solids and Sb2S3-PVA films were conducted.2)Using high-doped erbium-doped fiber(Er110-4/125)as the gain medium and Sb2S3 as the SA,the operation of a high-doped erbium fiber pulse laser was successfully achieved.In the experiment,two longer cavity lengths were designed to facilitate the generation of multiple pulses,and the dispersion of the fiber was set to two different negative dispersion values for comparative experiments.In the～117 m cavity length fiber laser,mode-locked pulses,Qswitched mode-locked pulses,and multiple pulse soliton bunch pulse output were successfully achieved.The evolution of multiple pulse soliton bunches with pump power was studied.In the～64 m cavity length fiber laser,mode-locked pulses,multiple pulse soliton bunches,unordered multiple pulses,and soliton rains were successfully achieved.The evolution of multiple pulse soliton bunches with polarization variation was also studied.3)Using low-doped erbium-doped fiber(EDF,MP980)as the gain medium and Sb2S3 as the SA,the operation of a low-doped erbium fiber pulse laser was successfully achieved.In the experiment,three different cavity lengths were selected to adjust the dispersion of the fiber to the negative dispersion region,near-zero dispersion region,and positive dispersion region,respectively.Different output parameters of the laser were controlled by selecting optical couplers(OCs)with different coupling rates.Various pulse output modes,including singlewavelength mode-locked pulses,single-wavelength bright and dark soliton pulse pairs,dualwavelength mode-locked pulses,harmonic mode-locked pulses,and Q-switched pulses,were successfully achieved.4)A neodymium-doped all-fiber laser and an ytterbium-doped all-fiber laser were constructed using Sb2S3 as an SA.Multiple-wavelength mode-locked pulse laser operation was achieved in both the neodymium-doped and ytterbium-doped fiber lasers. |
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