Multi-pass oscillator layout for high-energy mode-locked thin-disk lasers

TL;DR

This paper introduces a new multi-pass resonator design for mode-locked thin-disk lasers that enables energy scaling without stability region shrinkage, using concatenated optical segments and effective aperture modeling.

Contribution

The paper presents a novel multi-pass resonator layout that maintains stability with increased passes, facilitating higher energy scaling in thin-disk lasers.

Findings

The proposed design maintains stability regardless of the number of passes.

Effective Gaussian aperture modeling improves eigen-mode simulation accuracy.

A simple optical rearrangement can double the stability region of existing layouts.

Abstract

A novel optical layout for a multi-pass resonator is presented paving the way for pulse energy scaling of mode-locked thin-disk lasers. The multi-pass resonator we are proposing consists of a concatenation of nearly identical optical segments. Each segment corresponds to a round-trip in an optically stable cavity containing an active medium exhibiting soft aperture effects. This scheme is apt for energy and power scaling because the stability region of this multi-pass resonator contrarily to the 4f-based schemes does not shrink with the number of passes. Simulation of the eigen-mode of this multi-segment resonator requires considering aperture effects. This has been achieved by implementing effective Gaussian apertures into the ABCD-matrix formalism as lenses with imaginary focal length. We conclude proposing a simple way to double the stability region of the state-of-the-art layouts used in industry achievable by a minimal rearrangement of the used optical components.