Toward sub-cycle field shaping by molecular modulation in gasses and solids: Raman coherence at work

Sub-cycle field shaping by molecular modulation in gasses and solids are reported. Raman coherence in Raman-active crystals driven by shaped femtosecond pulses is shown. An optimal configuration for the driving pulses, with a compromise pulse duration which is long enough to produce a highly-coherent resonant excitation without interference from parasitic nonlinearities (such as self phase modulation) is shown. The multi-color beams (produced by molecular modulation) by means of a spherical mirror and a prism is combined, and then by using an acousto-optic pulse shaper the spectral phases are adjusted to obtain desired waveforms. Raman generation (in a CW regime) in gas-filled photonic crystal fibers is shown; this work may allow significant applications to metrology.