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Study Of Yb~(3+) Doped Double Clad Fiber Laser

Posted on:2007-08-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:J X ChenFull Text:PDF
GTID:1118360185456741Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Compared with traditional solid state laser, fiber laser has many merits, such as high efficiency, good beam quality, compact and good heat dissipation. Yb3+ doped fiber laser has been attracted greatly because of simple energy structure, no excited state absorption, and wide tunable range. Different from general fiber, double clad fiber has an inner clad at the outside of fiber core. In double clad fiber laser, pump light propagates in inner clad and is absorbed by doped fiber core. Laser can be produced in doped fiber core. Because of large geometrical size and numerical aperture (NA) of inner clad, high pump power can be coupled into the double clad fiber so that high output laser power can be yielded. In addition, thermal and nonlinear effects can limit the power scaling of fiber laser.In this paper, Yb3+ doped double clad fiber laser is studied in theory and experiment. The main work is as follows:1. Double clad fiber laser is introduced, including fiber structure, pumping method, state of art and application.2. Energy structure and transition cross sections of Yb3+ are presented. According to rate equations of fiber laser, the power distributions of pump and laser, the effects of output coupling reflectivity, scattering loss coefficient and wavelength of pump light on the characteristics of fiber laser are studied by shooting method. The results can help us design double clad fiber laser.3. One point side pumped double clad fiber laser is analyzed theoretically. The power distribution of laser in fiber, and the relationship between pumping position and output power are obtained for different pump power distributions.4. The experimental system of end pumped Yb3+ doped double clad fiber laser is set up. Some problems, such as end coupling, polishing of fiber end and wavelength controlling of laser diode, are solved. The single transverse mode double clad fiber laser with an output power of 3.87W and a slope efficiency of 70% is acquired.
Keywords/Search Tags:double clad fiber, fiber laser, power distribution, output characteristic, pumping method, thermal effect, stimulated Raman scattering
PDF Full Text Request
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