Compact 200 kHz HHG source driven by a few-cycle OPCPA

TL;DR

This paper introduces a highly efficient, high-repetition-rate high-order harmonic generation source driven by a few-cycle OPCPA, achieving significant XUV pulse energy at 200 kHz for advanced ultrafast experiments.

Contribution

It demonstrates a novel high-repetition-rate HHG source driven by a stable, few-cycle OPCPA with optimized gas target and high conversion efficiency, enabling new ultrafast spectroscopy applications.

Findings

Achieved ~10^{-6} conversion efficiency from NIR to XUV

Generated 6 fs pulses at 200 kHz with 9 μJ energy

Enabled potential for high-repetition-rate pump-probe experiments

Abstract

We present efficient high-order harmonic generation (HHG) based on a high-repetition rate, few-cycle, near infrared (NIR), carrier-envelope phase stable, optical parametric chirped pulse amplifier (OPCPA), emitting 6fs pulses with 9{\mu}J pulse energy at 200kHz repetition rate. In krypton, we reach conversion efficiencies from the NIR to the extreme ultraviolet (XUV) radiation pulse energy on the order of ~10^{-6} with less than 3{\mu}J driving pulse energy. This is achieved by optimizing the OPCPA for a spatially and temporally clean pulse and by a specially designed high-pressure gas target. In the future, the high efficiency of the HHG source will be beneficial for high-repetition rate two-colour (NIR-XUV) pumpprobe experiments, where the available pulse energy from the laser has to be distributed economically between pump and probe pulses.