Effect of Spectral Filtering on Pulse Dynamics of Ultrafast Fiber Oscillators at Normal Dispersion

Mode-locked oscillators are the building blocks to generate ultrafast pulses which can then be used for many applications, including optical communication, metrology, spectroscopy, microscopy, material processing, as well as many applications in the healthcare industry. Mode-locked fiber oscillators are especially popular for their compactness, efficiency, and beam quality compared to their solid-state counterparts such as Ti: Sapphire lasers. Apart from their practicality, the mode-locked fiber lasers are an interesting object for studies, as they represent dynamically rich nonlinear systems. For ultrafast fiber oscillators at normal dispersion, a spectral filter is the utmost important optical component that determines the behavior of these systems in terms of the spectral bandwidth, pulse duration, central wavelength of the output spectra, multipulse dynamics, pulse structure as well as pulse velocity. Recently, there is a growing interest in fiber based spectral filters as they facilitate the construction of all-fiber laser cavities. This dissertation investigates the laser performance parameters by developing an all-fiber spectral filter and exploiting its characteristics. Especially, this dissertation reports the first experimental observation of dissipative solitons of the complex Swift Hohenberg equation. This is very important as it births multiple future projects related to implementing higher order spectral filtering in mode-locked fiber lasers. Although most of the ultrafast oscillators in this dissertation are built at 1 nm, ideas to build mode-locked lasers at visible wavelengths are also presented along with primary numerical simulation and experimental results. Finally, all the upcoming research directions are discussed in detail