The Study of High Peak Power Ytterbium-doped Fiber Amplifier
Date Issued
2009
Date
2009
Author(s)
Lyu, Bo-Han
Abstract
Comparing with the traditional high peak power solid state lasers, Yb-doped fiber laser and amplifier have high surface to volume ratio for good heat dissipation. Even kW-level output power, Yb-doped fiber laser and amplifier can achieve more than 50 % optical conversion efficiency and near diffraction limit beam quality. As the invention of double cladding fiber, the pump laser can propagate in inner caldding, so low-beam quality but high-power semiconductor laser can be used. Therefore, the operation and maintenance costs can br reduced and the feasibility ofommercialization is improved. Thus, solid-state laser materials processing is bound to be replaced by Yb-doped fiber laser the in the future, because Yb-doped fiber lasernd amplifier architecture is simple and monolithic fiber laser system is possible. For next-generation lithography-extreme ultraviolet lithography, Yb-doped fiber laser cane emploted as high peak power source to produce plasma for generating extreme ultraviolet. Therefore, the importance of Yb-doped fiber laser and amplifier in lithography is apparent. In this thesis, I have collected some ytterbium-doped fiber amplifier theory and scripted pulsed and continuous-wave amplifier simulation program by Wolfram Mathematica 6.0. In experiment part, I finished the core-pumping pre-amplifier system and wrote a computerized control program for this system. Automatic optical power measurement program by National Instrument LabVIEW 8.2 were alsomplemented. In addition to the establishment of a stable operating and application systems, I made a comparison between numerical simulation and experiment result. Ibserved pump saturation effect of the core-pumped pre-amplifier. Several possible issues making simulation and experiment mismatch are discussed, such as doping concentration, signal laser mode diameter, pump overlap intergral, pump laser absorption crosssection and emission crosssecction, signal absorption crosssection and emission crosssection, spontaneous lifetime. Only by adopting the parameter of pumping quantum efficiency in the rate equation, the experiment result become in good agreement with the simulation. For pump saturated optical amplifier systems, pump quantum efficiency is more significant to output power, through the comparision of experiment, the pumping quantum efficiency of this system is about 0.975.
Subjects
optical amplifier
ytterbium-doped fiber amplifier
double cladding fiber
polarization maintained fiber
master-oscillator power amplifier
core-pumping
pumping quantum efficiency
Type
thesis
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