Study On High Power Ytterbium-Doped Fiber Lasers And Key Components

Ytterbium-doped fiber laser has born in1960s, and it has experienced half a century ofdevelopment. As the fiber manufacturing process, as well as semiconductor laserproduction technology has become more sophisticated, ytterbium-doped fiber laser hasdeveloped rapidly in the last decade. Now fiber laser plays an increasing role in the field ofscientific research, communications, industrial applications, as well as medical.Ytterbium-doped fiber laser is also faced with the challenge of some of the technologiesand key components in high-power and integrated direction.This thesis focuses on high-power ytterbium-doped fiber laser, as well as keycomponents in research. This work mainly from four aspects: First, according to the rateequation theory to simulate the theoretical model and output characteristics of fiber lasers;Secondly, study on the20W CW fiber laser pumped by fiber bundle combiner, and themothed of fabrication of fiber optic combiners; Then, the ytterbium-doped double-claddingfiber laser with300W output has experimental studied. Meanwhile, addressing a smallaperture opening diameter and cooling issues and the transmittance of the dichroic mirrorthermal stabilit, and the fiber end damage analysis of the problem have been solved.Finally, the fiber laser experiments and the key components in fiber Bragg grating forexperimental research and analysis. The main contents of this thesis are as follows:（1） The establishment of fiber laser theoretical model. Establish a theoretical model ofthe characteristic parameters of the laser pump optical power fiber laser systems with rateequation. We theoretical simulate the parameter of Yb³⁺-doped double-cladding fiber in thiswork.（2）20W fiber lasers with fiber bundle combiner and key components in this system.We introduce the fabricating of fiber bundle combiners, while the experimental analysis ofthe7×1fiber bundle combiners performance by Fiberhome. The experimental data provethat the overall transmittance of the optical fiber combiners can reach close to92%,insertion loss of0.4dB. The experimental test Yb³⁺-doped double-clad fiber absorptionefficiency of0.54dB/m, the optimum fiber length of about20m. We demonstrated that thefiber laser generates up to20.5W of continuous-wave output power at1106nm with a homemade D-shape inner cladding ytterbium-doped fiber. The slope efficiency is about75%.（3）300W Yb³⁺-doped double-clad fiber lasers and key components in the system. Wecarry out research on three key technologies and devices in high-power ytterbium-dopedfiber laser experiments. First, we use graphite as the diaphragm substrate, with its hightemperature resistance and high thermal conductivity performance. And determine the holediameter is2.8mm for the best; Second, by adjusting the cavity loss to solve the problem ofthe optical fiber input surface damage; Thrid, high purity Zr2O3as made of thin-filmsubstrate with high thermal stability of dichroic mirror. The transmittance is92%whenpump power reaching more than400W. Therefore, It works stably when the output powerreached332W with the slope efficiency of78.5%, and the threshold power of7.6W. Itshows the central wavelength of1104nm, and spectral width of13.6nm, and less than2%pump light has left.（4） Fabricate and analysis of fiber Bragg grating and all-fiber laser. In this paper, thescheme of femtosecond laser inscribed fiber grating using the phase mask method isinscribed in the the HI1060ordinary single-mode fiber and solid-state band gap photoniccrystal fiber grating. The peak wavelength and reflectivity are1063.93nm and1063.95nm,99.97%and84.76%, for the two peaks, respectively has observed in HI1060single modefiber. And the spectral width is0.5nm. Dual-peak structure is observed in the transmissionspectrum of the induced grating in all-solid bragg photonic bandgap fiber, which is formedby the coupling between the forward-propagating fundamental core mode and thebackward-propagating core mode or supermode. Sensing characteristics of the device areinvestigated experimentally by employing strain and temperature tests, and similar behavioris obtained for both resonant peaks. The strain and temperature sensitivities are0.968pm/με and12.01pm/oC, and0.954pm/με and12.04pm/oC, for the two peaks, respectively.Finally,the all-fiber laser has established with output wavelength1064.0215nm andlinewidth0.145nm by using HI1060single-mode fiber grating.