Study On Luminescence And Laser Characteristics Of Ytterbium Doped Fiber

Rare earth ions doped active optical fibers and their lasers are widely applied in many fields,such as illumination,fluorescence detection,biomedicine,industrial welding,sensing,ranging and so on,because of their high beam quality,stable performance and wide range of wavelengths selection.The light sources of ytterbium-doped fibers have been the research topics in the field of science,owning to their small quantum defects and high beam quality.In this paper,the theoretical and numerical analysis and experimental study of ytterbium-doped optical fiber lasers are carried out systematically.Firstly,the characteristics of ytterbium ions,energy level structure,luminescence characteristics,fiber structure and recent lasers development are systematically analyzed and introduced in this paper.Then,the basic characteristics of ytterbium-doped fiber materials,the preparation method of ytterbium-doped mandrel and the design principle of ytterbium-doped single-mode fibers are analyzed theoretically.The ytterbium-doped fiber laser model and the working principle of pulse and wavelength tuning are analyzed,which provide useful guidance and analysis for the following simulation and experiments.Based on the above theory,the preparation process of nanoporous glass was explored experimentally.The important characteristics of nanoporous glass,such as pore channel,morphology and specific surface area,were studied.The method of synthesizing gold nanoparticles with different characteristic distribution as a new doping matrix was proposed for the first time.The fluorescence enhancement of ytterbium ion was controlled by surface plasmon effect of gold nanoparticles.The ytterbium-doped single-mode optical fiber has been successfully fabricated through the regulation of fluorescence enhancement and wire drawing technology.At the same time,based on the flexibility of the preparation of ytterbium-doped active core in porous glass and the controllability of doping,a single transverse mode multi-core photonic crystal fiber with a mode area of 41800?m~2 is designed.The characteristics of high doping rare earth in nanoporous glass are fully combined with the flexibility of the design of multi-core photonic crystal fiber.Leakage mode loss is reduced to cladding,and only in-phase fundamental mode transmission exists in the core,therefore,it can keep single mode transmission characteristics with the large mode area structure.Then,based on the characteristics that ytterbium-doped fiber can obtain high gain,a fundamental mode-locked Ytterbium-doped fiber laser with GHz repetition rate is constructed and numerically simulated.The relationship between laser mode-locking stability and cavity parameters,including laser gain,dispersion,laser cavity output percentage and bandwidth,is systematically studied.On these results,the cavity length is further shortened,and the higher GHz weight is calculated and analyzed.The stability region of complex-frequency mode-locked ytterbium-doped fiber laser.A 1190 nm ytterbium-doped fiber laser and a 1150 nm Raman fiber laser are experimentally constructed,respectively.Then,a Holmium-doped fiber laser was constructed by cascaded laser and a Ho-doped fiber made in our laboratory.The laser wavelength of 1200 nm was obtained.Two tunable fiber laser setups were constructed by using a diffraction grating.The laser output of Ho-doped fiber laser was obtained for the first time at the wavelength of 1177-1201 nm.