Study On Novel High-power Cladding-pumped Fiber Laser

In this paper, the research development of high-power fiber laser is summarized generally; the fundamental principle and applications of high-power fiber laser are introduced. The key technologies of high-power fiber laser including clad-pumping; fiber coupling and resonant cavity are described. The structure and transmission principle of double clad fiber is introduced; output characteristics and absorbability in double clad-fiber are theoretically analyzed. The structure of the energy level of Yb³⁺ and the basic characteristics of the Yb³⁺-doped double clad fiber are discussed; Based on rate equations and transmission equations, the theory model of high power linear cavity Yb³⁺-doped double clad fiber lasers is developed. By using numerical calculation, the effects of fiber length, loss and reflectivity of fiber Bragg grating (FBG) as the output mirror on laser output power and threshold pump power are discussed. The results provide theoretical guidance for design and fabrication of high power fiber laser. Based on fiber grating, an all-fiber double-clad fiber laser is designed and developed; Taper fiber is used to reduce the connection loss between DCF and laser diode. With the all-fiber cavity design, under the pumped power of 17.2W, the single-mode laser output power at 1070nm is up to 10.5W with a slope efficiency of 61 %. By exploiting pulsed pump light and stimulated Brillouin scattering (SBS) of fiber core, we realized pulse compression with all-fiber structure. A pulse with duration of 400ns, average power of 2.53W and the repetition rate of 15 kHz is obtained. The results of the experiment are explained qualitatively.