Ultrafast Erbium Doped Fiber Laser And Soliton Self Frequency Shift Produced By Ultrashort Pulse In A New Band

Recently,fiber lasers have attracted great attention and been widely used in many fields,and the physical phenomena in ultrafast fiber lasers have been intensively studied.At the same time,ultrafast fiber laser is still expanding its application field.In this dissertation,the dissipative soliton mode-locked fiber laser is based on the nonlinear polarization rotation technology.The ultrashort pulses generated by the mode-locked laser can be used to produce 1.7 ?m femtosecond laser pulses via soliton self-frequency shift in the dispersion shifted fiber.And the implementation may have a special significance in the biomedical field and is prospective to expand the transmission capacity of optical communications.Experimental and theoretical work has been carried out based on these techniques.1.We have introduced the background and an overview about progress of ultrafast fiber laser development.2.Based on the relevant theories of conventional optical fiber,the mode transition property is discussed when the pulse transmit in the step-index optical fiber,and the generalized nonlinear Schrodinger equation are derived.The dissipative soliton fiber laser is numerically simulated,and the feasibility of our model for analyzing the soliton selffrequency shift is also verified.3.The principle of producing ultrashort pulse by mode locking are introduced and the passive mode locking in fiber laser are studied.We have demonstrated a mode-locked laser with positive intra cavity dispersion which can be used to produce new band ultrashort pulses.The mode-locked fiber laser is able to generate 95 fs ultrashort pulses with large energy and the central wavelength is around 1.6 ?m.4.Based on SSFS,we demonstrate the generation of ultrashort pulses emitting at 1.7-?m band in a common dispersion shifted fiber(DSF)pumped by an ultrafast Er-doped fiber laser.Sub-200 fs pulses in the range from 1.70 to 1.74 ?m have been achieved with >76 % conversion efficiency.Moreover,the SSFS based laser light source is all fiber structured and has an ultrashort pulse width.The result shows the potential of such a convenient and low cost method to produce an ultrashort fiber pulses in 1.7 ?m band and ensures its promotion.In this paper,ultrafast erbium doped fiber laser based on nonlinear polarization rotation technique is studied,and femtosecond pulses at 1.7-?m are generated via soliton self-frequency shift.It is expected to be applied in biological optics imaging and other fields.