Strong-Field Physics in Intense Few-Cycle Laser Fields: From Carrier-Envelope-Phase Effects to Waveform Engineering

The generation of intense few-cycle laser pulses with a stabilized carrier-envelope phase (CEP) has enabled unprecedented control of strong-field laser–matter interactions on an attosecond time scale. Few-cycle laser fields allow direct manipulation of the instantaneous electric-field waveform, making the CEP and other waveform parameters fundamental tools for steering electron dynamics. In this review, we present a comprehensive overview of the role of waveform control in strong-field processes driven by intense few-cycle laser pulses. We discuss the generation and characterization of few-cycle pulses and summarize the influence of the CEP on above-threshold ionization, high-order above-threshold ionization, nonsequential double ionization, high-order harmonic generation, and laser-assisted scattering and radiative recombination. Particular attention is devoted to bichromatic laser fields, where waveform engineering is achieved not only through the CEP but also by controlling the relative phase, polarization, frequency ratio, and intensity of the field components. These additional degrees of freedom provide powerful control knobs for tailoring electron trajectories, photoelectron momentum distributions, harmonic spectra, cutoff energies, and the polarization properties of the emitted radiation. Representative theoretical results are used to illustrate how waveform engineering enables efficient control of strong-field phenomena. The developments reviewed here demonstrate that waveform-controlled few-cycle laser fields have become indispensable tools for attosecond science, ultrafast spectroscopy, and coherent control, while continuing to stimulate new theoretical and experimental advances in strong-field physics. Overall, this review highlights the evolution of strong-field physics from CEP-controlled interactions to comprehensive waveform engineering, where multiple independently tunable laser parameters enable precise control of ultrafast electron dynamics and light emission.