Two-micron Fiber Lasers And Their Nolinear Effects

Since urgent needing of eye-safe lasers and unique application areas of 2?m laser,thulium doped fiber lasers attracted more and more attention.During recent decades,2?m fiber lasers had developed tremendously.Nevertheless,the improvement of 2?m fiber laser is still facing severe challenges,which implies the huge development opportunity as well.Firstly,with regard to CW single frequency 2?m laser with narrow linewidth,power promotion of which is restricted by stimulated Brillouin scattering.Secondly,as to the 2?m mode locked fiber laser,the inherited features of traditional saturable materials narrowed their applications.In addition,it is desired to develop new technology to overcome soliton area theorem,what limits pulse energy in soliton mode locking laser.At last,transfer efficiency and thus thermal loading are important factors for development of high power thulium doped fiber laser.Responding to aforementioned challenges and urgent application requirements,research works has been conducted in 2?m fiber lasers and the valuable achievement was made consequently.Find the main content of the research as below:1.Intrinsic characteristics of traditional single frequency laser with structure of DBR or DFB limited their performance,such as low output power and large possibility of mode hoping.In this research,a thulium doped fiber amplifier is designed firstly,output of which is used as Brillouin pump wave for Brillouin single frequency fiber laser.Based on effect of linewidth narrowing,phase noise smoothing and relative higher transfer efficiency in Brillouin single frequency fiber laser,2?m single frequency laser was achieved with watt-level output power?1.04 W?,ultra-high SNR?62 dB?and ultranarrow linewidth?8 kHz?.2.Nowadays,SESAMs?Semiconductor Saturable Absorber Mirror?,graphene,MoS₂ and black phosphorus are extensively used in mode locking laser.However,their application is still limited due to their own characteristics.Therefore,the research on the exploring of new 2D materials is still research hot point.In this dissertation,we introduced a new 2D material of Fe-g-CN and researched its linear and nonlinear absorption features through experiment,on the strength of this 2D SA,we achieved pulses with 2.2ps duration successfully and verified that Fe-g-CN could be used as 2D SA in 2 um mode locking.3.Dissipative soliton resonance?DSR?provides a new method to obtain high pulse energy in mode locked lasers.In DSR system,dispersion and saturable absorbor play important role to obtain high-energy pulse.In this research,DSR is realized in SESAM locked 2?m thulium doped fiber laser with high net normal dispersion.Consequently,DSR pulses with duration of 161ns and energy of 20.6-nJ was successfully achieved in this structure.4.Large mode area and double clad thulium doped fiber is a fundamental component in high power laser and amplifier.Transfer efficiency and photo darkening effect could be affected with varying degree by different manufacturing methods.Photo darkening effect is mainly induced by ions clustering in manufacturing,which could cause gradually increasing loss at wavelength of pump and laser,and transfer efficiency and reliability decreasing.We fabricated two types of thulium-doped fiber through vapor and solution doping method and measured their performance in identity setup of fiber laser.Through the experiment,compared to solution doping method,photo darkening in thulium doped fiber manufacturing through vapor doping method is slower,and the fiber performed more stable.