Four years after the first demonstration of Light Amplification by Stimulated Emission of Radiation in a Ruby crystal by Theodore Maiman in 1960, C. J. Koester and E. Snitzer transferred this new and groundbreaking laser concept to Neodymium doped glass waveguides and paved the way for modern fiber lasers. The prediction of low loss optical fibers for long-distance optical communication by C. Kao in 1966 and the first demonstration of a fiber with only 20 dB/km loss by Corning laboratories in 1973 triggered major R&D investments in the second half of the 20th century. The development of specialty optical fibers was facilitated by the introduction of the stack-and-draw fiber manufacturing technique, which enabled the fabrication of more complex fiber structures and expanded the application space of optical fiber technology. This dissertation is divided into four chapters. The first chapter provides a short review of the history of optical fibers and their application in fiber laser systems as well as an outline of this dissertation. In the second chapter, Ytterbium based single mode high average power fiber amplifiers and their average power limitations are discussed. In particular, the concept of spatially confining the gain to certain regions of the fiber's core is discussed in detail as one strategy to overcome some of these limitations. Furthermore, the development of a narrow line width high power fiber laser system is discussed. The third chapter discusses the potential of disordered glass-air Anderson localization fiber for broad band super continuum generation and the fourth chapter discusses the pulse energy scaling potential of Ytterbium doped multicore fiber saturable absorbers for ultrafast fiber oscillators.


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Graduation Date





Schulzgen, Axel


Doctor of Philosophy (Ph.D.)


College of Optics and Photonics


Optics and Photonics

Degree Program

Optics and Photonics




CFE0008837; DP0026116





Release Date

December 2026

Length of Campus-only Access

5 years

Access Status

Doctoral Dissertation (Campus-only Access)

Restricted to the UCF community until December 2026; it will then be open access.