# Generating carrier-envelope-phase stabilized few-cycle pulses from a free-electron laser oscillator

## TL;DR

This paper introduces a method to produce CEP-stabilized few-cycle pulses using a free-electron laser oscillator, enabling advanced applications in high-harmonic generation, x-ray frequency combs, and chemical control.

## Contribution

It presents a novel scheme for CEP stabilization in FEL oscillators through external seed injection synchronized with the electron bunches.

## Key findings

- Demonstrates feasible generation of CEP-stabilized few-cycle pulses
- Enables high-energy attosecond and zeptosecond science applications
- Facilitates development of broadband x-ray optical frequency combs

## Abstract

We propose a scheme to generate carrier-envelope-phase (CEP) stabilized few-cycle optical pulses from a free-electron laser oscillator. The CEP stabilization is realized by continuous injection of CEP-stabilized seed pulses from an external laser to the FEL oscillator whose cavity length is perfectly synchronized to the electron bunch repetition. Such CEP-stabilized few-cycle FEL pulses will be an efficient driver for exploring high-harmonic generation at energies 1-10~keV for attosecond and zeptosecond science, broad-band x-ray optical frequency combs and coherent control of chemical reaction.