Generation of sub-femtosecond pulses is of wide interest to the physics community due to the possibility of probing electronic motion on ever shorter time scales. Over the last decade, several approaches have been suggested and studied to generate such short pulses in the optical region of the spectrum. Despite considerable effort, these approaches have not been able to produce pulses shorter than 3.5 femtoseconds.; In this thesis, we describe a new approach for generating sub-femtosecond laser pulses in the optical region of the spectrum. The basic idea behind our approach is to strongly drive a selected Raman resonance of a diatomic molecule with two laser fields and prepare the molecules in a state of maximum coherence. These vibrating molecules then act as a local oscillator and modulate the driving lasers producing coherent radiation covering infrared, visible and ultraviolet spectral regions. The spectrum is produced at low gas cell pressure and collinearly with the driving lasers with phase-matching playing a negligible role. Our experiments in molecular hydrogen and deuterium demonstrate generation of more than 200 coherent sidebands ranging from 195 nm to 3000 nm in wavelength. We then use a subset of this wide spectrum and synthesize a few femtosecond pulses. Our measurements indicate the generation of the shortest pulses ever generated in this region of the spectrum.
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