Proposals for gain cascading in single-pass of a free-electron laser oscillator

TL;DR

This paper proposes a multi-stage undulator FEL oscillator design that enables gain cascading in a single pass, significantly enhancing pulse power and energy in various spectral regions.

Contribution

It introduces a novel multi-stage undulator configuration for FEL oscillators to achieve gain cascading in a single pass, improving performance over classical designs.

Findings

Theoretical analysis confirms the feasibility of gain cascading in FEL oscillators.

Numerical simulations demonstrate increased pulse power and energy in infrared and X-ray regions.

The approach can produce shorter pulses with higher peak power and energy.

Abstract

The low-gain free-electron laser (FEL) oscillators are cutting-edge tools to produce fully coherent radiation in the spectral region from terahertz to vacuum ultraviolet, and potentially in hard X-ray. In this paper, it is proposed to utilize an FEL oscillator with multi-stage undulators to enable gain cascading in a single-pass, making it possible to achieve shorter single pulse lengths, higher peak power, and even higher pulse energy than classical FEL oscillator. Theoretical analysis and numerical simulations in the infrared and hard X-ray regions show that our proposal is effective.