Performance Scaling of Ultrafast Laser Systems by Coherent Addition of Femtosecond Pulses

TLDR

Ultrafast lasers have dramatically increased power, enabling diverse applications, yet recent physical limits make further scaling increasingly difficult. The study reviews experimental implementations of spatially and temporally separated amplification with coherent addition to overcome scaling limits. The authors examine fiber‑based, spatially and temporally separated amplification schemes that coherently add ultrashort pulses, leveraging the high average power and parallelizable single‑pass design of fiber amplifiers. These approaches enable laser parameters once thought unattainable, demonstrating significant performance scaling.

Abstract

In the last decades, ultrafast lasers and amplifiers have achieved an extraordinary power increase and have enabled a plethora of scientific, medical or industrial applications. However, especially in recent years, it has become more and more challenging to keep up with this pace since intrinsic physical limitations are becoming difficult to avoid. A promising way to get around this problem is the technique of spatially and/or temporally separated amplification and subsequent coherent addition of ultrashort pulses. It turns out that fiber amplifiers are perfect candidates for this concept due to their outstanding average-power capability and their simple single-pass setups, which can be easily parallelized. Herein we provide an overview of the most important experimental implementations of this concept and recent results. We discuss the ability of these approaches to generate laser parameters that, only a few years ago, seemed impossible to achieve.