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Femtosecond fiber lasers and amplifiers based on the pulse propagation at normal dispersion

Author
Chong, Chin Yu
Abstract
The applications of ultrafast optical pulses exploded in last two decade since the discovery
of a mode-locked Ti:sapphire laser. Ti:Sapphire lasers are great ultrafast optical
pulse sources but they are not suitable for some applications since they are are bulky,
expensive, and unreliable. So far, solid-state lasers including Ti:sapphire lasers are dominant
as ultrafast pulse sources. However, compact, inexpensive and stable fiber lasers
recently started to replace solid-state lasers. Even though fiber lasers have many practical
advantages, the performance of fiber lasers is still below that of the solid-state fiber
lasers. Among many kinds of fiber lasers, a mode-locked ytterbium (Yb)-doped fiber
lasers has been received a broad attention for medical applications such as the biomedical
imaging. This thesis summarizes the e ort of the Yb-doped fiber laser performance
enhancement utilizing the pulse propagation at high normal dispersion.
In this thesis, femtosecond Yb-doped fiber lasers without anomalous dispersion element,
so called all-normal-dispersion (ANDi) fiber lasers, are demonstrated based on
unique pulse shaping mechanism of the chirped pulse spectral filtering. ANDi fiber
lasers represent a new paradigm for femtosecond pulse generation. This new type of a
laser is very practical because it avoids the technical challenges of providing anomalous
dispersion without loss at 1um. Useful features of the ANDi fiber lasers have been
demonstrated experimentally in terms of the pulse energy, the pulse duration, the environmentally
stability, and controllable multipulsing states. Pulse energies > 20 nJ with
>100 kW peak power and pulse durations <100 fs are experimentally demonstrated.
Theoretical studies indicate that further performance improvement is quite possible.
The ANDi fiber lasers are not only practical femtosecond lasers, but also great research
tools for ultrashort pulse propagation phenomena. Dissipative solitons of complex cubic
quintic Ginzburg-Landau equation are demonstrated experimentally from an all-normal
dispersion fiber laser.
This thesis is not limited to the demonstration of ANDi lasers. It also covers interesting
pulse propagation phenomena in fiber lasers and amplifiers. The formation
of a second-order dispersion managed soliton, which is referred as an antisymmetric
dispersion managed soliton, in a fiber laser with a strong dispersion map is demonstrated.
Finally, the thesis describes the chirped-pulse-amplification system performance
enhancement with proper nonlinear phase shift and third-order dispersion.
Date Issued
2008-05-19Has other format(s)
bibid: 6397056
Type
dissertation or thesis