The Research On Ytterbium Doped Q-switched Fiber Laser Based On Novel Two-dimension Material

Pulse fiber laser is widely used in the fields of biological medicine,materials processing,info-communications owing to their advantages of narrow pulse width,high pulse energy and peak power.Pulse laser can be achieved by Q-switched technology and mode-locked technology.Q-switched technology include active Q-switched,passive Q-switched,and hybrid Q-switched.Comparing with active Q-switched and hybrid Q-switched,passive Qswitched fiber laser benefits from its merits of simple and compact all-fiber configurations owing to there aren't any modulator in the laser cavity.There are two major types of passive Q-switched technology,one is configuring saturable absorber(SA)into laser cavity and the other is replacing SA with artificial SA(such as nonlinear optical loop mirror(NOLM),Nonlinear Polarization Rotation(NPR)).Q-switched fiber laser based on SA have been acquired considerable attentions for its merits of low cost and efficient.Considerable energy and money are throw into the study of novel SAs which possess excellent non-linear optical performance.And the fruit is remarkable.Investigations on novel SAs,such as saturable absorber mirrors(SESAMs),graphene,transition-metal dichalcogenides(TMDs),topological insulator(TI),and black phosphorus(BP)have been significantly developed and employed as the effective SAs for pulse emission in fiber lasers during the last decades.And innovative SA fabricate methods have been put forward and improved.But the widely application of those SAs is restricted by their defects.There are considerable realistic values and theoretical meanings in the study of novel SAs which possess excellent performance.In this work,the saturable absorption characteristics at 1 ?m of two types novel SAs(BP and ReS2)has been carried out.And Q-switched operation was achieved by configured SAs with Yb-doped ring fiber laser.1.Raman spectrum and AFM map has been carried out to identify the properties of BP nanosheet which fabricated by micro-mechanical exfoliation.The PDMS film/BP nanosheet/microfiber/BP nanosheet/ PDMS film structure BP SAs was fabricated and inserted into Yb-doped ring fiber laser.stable and reliable Q-switched operation at 1064 nm can be realized via interaction between few layers BP flakes and the evanescent field of the laser.The laser allows Q-switched pulse generation with a repetition rate in the range of 26-76 kHz and a pulse duration in the range of 5.5-2.0 ?s,by varying the pump power from 38 mW to 100 mW.Benefiting for the relative large interaction area,the SAs possess relative high photo damage threshold of 32 mW.The PDMS sandwich configured BP SA enables us to have an effective protection for the BP flakes when the device is used in atmosphere.2.The exfoliated ReS2 nanosheet was deposited to the end-facet of a fiber connector to form a fiber integrated SA device.The ReS2 flake is characterize by Raman spectroscopy and AFM.The saturable absorption property of ReS2 SA was investigated with twin-detector measurement method,which based on a home-made mode-locked Yb-doped picoseconds pulse fiber laser.Stable Q-switched pulse train is observed when the pump power is increased to 56 mW.When the pump power is adjusted from 56 mW to 200 mW,the pulse duration varies from 3.32 ?s to 1.56 ?s and pulse repetition rate increase from 52 kHz to 134 kHz,corresponding to pulse energy increases from 6.06 n J to 13.02 n J and peak power increases from 1.83 mW to 8.13 mW,respectively.So far,this is the first report in the 1 ?m with ReS2 SA for short-pulsed generation.