Single attosecond light pulses from multi-cycle laser sources

High harmonic generation provides a means of producing attosecond pulses of light which are the shortest, controllable probes available to science for time-resolving ultrafast dynamics. We review techniques based on high harmonic generation for generating single attosecond pulses using high-power, multi-cycle laser sources, including optical-, polarisation-, and ionisation-gating schemes as well as techniques based on field synthesis. By significantly reducing the technical demands placed on the driving laser, these techniques have the potential to greatly broaden the application base for attosecond pulses.