Research On Soliton Nonlinearity In Erbium-doped Fiber Lasers

Passive mode-locked fiber lasers have been studied extensively and deeply in recent decades due to their advantages of good stability,small size and convenient operation.In fiber lasers,solitons exhibit a wealth of dynamic properties due to a combination of nonlinearity,dispersion,gain,and loss during propagation.Based on various cavity designs,passively mode-locked fiber lasers can generate various coherent and stable optical pulses.Therefore,the study of the dynamic characteristics of various soliton nonlinear phenomena using fiber lasers has important academic value and practical significance for the development of laser technology.In this paper,an erbium-doped fiber laser is built.Under the condition of reasonable design of laser cavity parameters,the fiber laser can obtain various kinds of rich nonlinear phenomena of solitons.The main research contents include:1.The background of fiber lasers and their application value are briefly described.Meanwhile,the characteristics of erbium-doped mode-locked fiber lasers and their research status at home and abroad are described.2.Three kinds of passive mode-locking techniques and their structures are described.The transmission theory of optical pulse in optical fiber is introduced,and the mode-locking principle and characteristics of nonlinear polarization rotation(NPR)technology are emphasized.3.A dual-wavelength switchable fiber laser is studied.Dual-wavelength modelocking can be achieved at 1533.2 nm and 1557.2 nm in erbium-doped fiber laser by using NPR mode-locking technology.Meanwhile,mode-locking can be switched between the two wavelengths.In addition,three wavelength mode-locking and multiple pulse mode-locking are also observed.The experimental results are helpful for understanding the soliton dynamics of dual-wavelength mode-locked fiber lasers.4.Research on trapezoidal noise pulse and harmonic pulse.The characteristics of high energy trapezoidal noise pulse and harmonic trapezoidal pulse in large anomalous dispersion fiber laser were studied by NPR technology.The structure,working principle and output characteristics of the laser were analyzed.The results are helpful to understand the output characteristics of high energy trapezoidal noise pulsed fiber laser and can be used as a multifunctional light source with potential application value.5.Research on dissipative solitons and soliton molecules in a slight-normal dispersion fiber laser.In this paper,the dispersion management of fiber laser is obtained.Meanwhile,wideband dissipative solitons and various soliton molecules can be observed in the slight-normal dispersion region.A dissipative soliton with bandwidth of 56.5 nm was obtained.By controlling the laser cavity parameters,various types of soliton molecules can be observed in fiber lasers,including conventional soliton molecules and unconventional structural soliton molecules.Soliton molecules exhibit different structural characteristics on the autocorrelation trace lines,which are related to soliton number,soliton strength and soliton separation within the soliton molecule.This result is helpful to enrich the soliton dynamics of fiber lasers in the slight-normal dispersion range.