Sub-cycle control of attosecond pulse generation using two-colour laser fields

Strong field laser-matter interaction is intrinsically a sub-cycle phenomenon, which is clearly illustrated by the generation of attosecond pulses through the high-order harmonic process. Therefore, to control strong field processes the structure of the field driving the generation has to be controlled on a sub-cycle level. One approach is to use phase stabilized few-cycle driving pulses and vary the carrier-envelope phase of these pulses; an alternative method is to use longer pulses and include the second harmonic to tailor the field structure.