The Research On Passively Q-Switched Fiber Laser Based On Rhenium Diselenide

Ultrashort pulse laser has important applications in many areas,such as material processing,optical communications,biomedicineand,thanks to the high peak power,broad bandwidth,and short pulse duration.There are two methods to achieve pulse emission of fiber lasers,including Q-switching and mode-locking.The passively Q-switched and passively mode-locked fiber lasers based on saturable absorbers are simple,compact and economically efficient.The semiconductor saturable absorption mirrors?SESAMs?with some disadvantages,such as complicated preparation process,heavy price,and narrow operation bandwidth which limits its widespread application in fiber laser.Commonly used SAs include graphene,transition metal chalcogenides?TMDs?and balck phosphorus?BP?which can be used in Q-switched laser for its excellent optical and optoelectronic properties.As a typical TMDs,rhenium diselenide?ReSe₂?has a bandgap in the range of1.26 eV to 1.32 eV.ReSe₂ has rhe layer-dependent bandgap value and unique properties such as anisotropic crystal structure.In this paper,the nonlinear saturable absorption characteristics of ReSe₂ were characterized by the twin-detector measurement system.The ytterbium-doped and erbium-doped fiber laser with ReSe₂ saturable absorber was successfully constructed,and the stablely Q-switched pulse based on ReSe₂ saturable absorber at 1?m and 1.5?m were attained.The following is the main content:ReSe₂ nanosheets were prepared by mechanical exfoliation method,and the saturable absorption characteristics of ReSe₂ at 1064 nm were measured by the home-made twin-detector measurement system.The modulation depth,saturation intensity and nonsaturable loss of ReSe₂ were 28%,9.56 MW/cm² and 64%,respectively.It can be measured that the linear transmission of ReSe₂ saturable absorption device is about 6.9%at1054.23 nm in experiment.The ReSe₂ saturable absorption device is put into the cavity to achieve Q-switched laser.When the pump power increased from 50 mW to 100 mW,the repetition ratecan be tuned continuously from 31.6 kHz to 68.7 kHz and the pulse width decreased from 3.77?s to 2.87?s.Meanwhile,the single pulse energy varied from 49.72 nJ to 81.62 nJ.It is firstly proposed with the ReSe₂ at 1?m fiber laser,to the best of our knowledge.In experiment,the saturable absorption device based on ReSe₂ was prepared by mechanical exfoliation method,and the stablely Q-switched fiber laser was achieved.Erbium-doped fiber laser based on ReSe₂ saturable absorber was constructed with a central wavelength of 1532.94 nm and a corresponding 3dB bandwidth of 0.145 nm.When the pump power was changed from 160 mW to 530 mW,the repetition rate increased from14.15 kHz to 70.45 kHz,and the pulse width decreased from 11.2?s to 1.77?s.