| Observation and control of ultrafast events requires optical pulses that are shorter than the characteristic time scales of the processes in question. For the last two decades, the once steady progress toward shorter optical pulses has been stalled at a pulse width of a few femtoseconds. Recent advances have reignited this progress, and promising results have been reported by many groups.; This thesis documents our Raman approach to generating ultrashort pulses. Our method prescribes phase-locking a wide spectral bandwidth of coherent sidebands produced from a coherently oscillating molecular medium. When two sufficiently intense laser fields are slightly detuned from a Raman transition, they will prepare the molecules in a superposition of vibrational states. This oscillating ensemble of molecules will modulate the two driving lasers, producing equidistant, collinear, and mutually coherent sidebands spanning over 4∼octaves of bandwidth. The refractive index modulation is strong enough to allow the first observation of Raman self-focusing and self-defocusing. By cascading modulators, it is possible to achieve a multiplicative increase in the number of generated sidebands. The mutual coherence of the generated sidebands permits the synthesis of trains of single-cycle optical pulses. |
