# Phase Control of Attosecond Pulses in a Train

## TL;DR

This paper demonstrates precise phase control of attosecond pulse trains generated by high-order harmonic generation through spectral phase and CEP adjustments, enabling better manipulation of ultrafast processes.

## Contribution

It introduces a method to control the relative phase and CEP of consecutive attosecond pulses by adjusting the spectral phase and CEP of the driving laser.

## Key findings

- Achieved high degree of phase control over attosecond pulses
- Validated experimental results with semiclassical theoretical analysis
- Demonstrated control using dispersion in glass

## Abstract

Ultrafast processes in matter can be captured and even controlled by using sequences of few-cycle optical pulses, which need to be well characterized, both in amplitude and phase. The same degree of control has not yet been achieved for few-cycle extreme ultraviolet pulses generated by high-order harmonic generation in gases, with duration in the attosecond range. Here, we show that by varying the spectral phase and carrier-envelope phase (CEP) of a high-repetition rate laser, using dispersion in glass, we achieve a high degree of control of the relative phase and CEP between consecutive attosecond pulses. The experimental results are supported by a detailed theoretical analysis based upon the semiclassical three-step model for high-order harmonic generation.