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Mode-Locked Fiber Lasers: Development and Application

TitleMode-Locked Fiber Lasers: Development and Application
Publication TypeThesis
Year of Publication2009
AuthorsHudson, DD

The field of mode-locked fiber lasers has grown tremendously over the last 10 years. In the last few years, in particular, this class of laser has moved from just offering a low cost, rugged and compact source of ultrashort pulses to offering state of the art ultrashort pulses. Rapid progress in fiber development has lead to a variety of specialty fibers: highly nonlinear fiber for various wavelength ranges, high dopant gain fiber, double-clad high gain fiber, and dispersion compensating fiber (to name just a few). These fundamental developments resulted in higher performance fiber laser systems. For instance, the high dopant gain fiber and the nonlinear fiber resulted in the ability to make fiber frequency combs at any wavelength. The double-clad fiber has allowed researchers to push the average power of Yb fiber lasers to >10 W; a level which is already above that offered from the popular Ti:sapphire system.

In this thesis, Erbium based mode-locked fiber lasers are examined from a development and application point of view. The first two chapters review some of the basic concepts that are used throughout this thesis. Chapter 3 covers a crucial advance necessary for fiber lasers to be used in precision experiments: frequency control and frequency dissemination over fiber links. The first point is accomplished with a fast intra-cavity actuator, while the second point is addressed using a stabilized fiber link. Chapter 4 then reviews two atomic physics based experiments that used stabilized fiber lasers.

The next two chapters describe and present characterization for a new method of achieving a mode-locked fiber laser based on a device known as a waveguide array. We believe this method could yield one of the most robust and compact mode-locked fiber lasers ever created. The experiment detailed in Chap- ter 5 involved measuring the pulse shaping of these waveguide array devices via au- tocorrelation. This measurement was the first demonstration of pulse shortening in waveguide arrays. Further characterization in Chapter 6 measured the effects of multi-photon absorption on the discrete spatial soliton that is formed at high peak power in the waveguide array. This experiment showed that multi-photon absorp- tion in the device effectively clamps the spatial soliton power distribution, with increases beyond a certain peak intensity causing virtually no change in the output distribution. The last experiment in Chapter 6 details a measurement of the full electric field shaping of the waveguide array using Frequency-Resolved Optical- Gating. Analysis of the data shows that the waveguide array has a spectral phase attraction point. Thus, any value for the input spectral phase is transformed, upon traveling through the waveguide array, into one output spectral phase. The last chapter provides a big picture overview of the topics covered in this thesis, and takes a look at the future directions in which this work is headed.