This dissertation reports the synthesis of unique Si0₂ based nanostructures by exposing glass samples to MHz repletion rate femtosecond laser irradiation. A three-dimensional fibrous nanoparticle agglomerate network was observed on soda-lime glass (73% SiO + other compounds) when exposed to femtosecond laser irradiation at 8.4 MHz and 12.6 MHz repetition rate and 0.5 ms dwell time, in air. By irradiating silica glass (96% SiO₂+ trace elements) sample under ambient conditions with femtosecond pulses at 12.6 MHz and dwell time in excess of 3.0 ms; long continuous nanofibers of extremely high aspect ration (certain fibers up to 100000:1) were obtained. The mechanisms that promote such nanostructures with distinct morphologies have been explored. A deeper insight into the fundamentals of femtosecond laser interaction with dielectrics led to the understanding that variations in bandgap alters ablation dynamics and dictates the response of glass to femtosecond laser irradiation, ultimately resulting in the formation of structures with dissimilar morphology on silica and soda-lime glass.