High-energy pulse self-compression and ultraviolet generation through soliton dynamics in hollow capillary fibres (1811.05877v2)

Abstract: Optical soliton dynamics can cause the extreme alteration of the temporal and spectral shape of a propagating light pulse. They occur at up to kilowatt peak powers in glass-core optical fibres and the gigawatt level in gas-filled microstructured hollow-core fibres. Here we demonstrate optical soliton dynamics in large-core hollow capillary fibres. This enables scaling of soliton effects by several orders of magnitude to the multi-mJ energy and terawatt peak power level. We experimentally demonstrate two key soliton effects. First, we observe self-compression to sub-cycle pulses and infer the creation of sub-femtosecond field waveforms - a route to high-power optical attosecond pulse generation. Second, we efficiently generate continuously tunable high-energy (1 to 16 $\mu$J) pulses in the vacuum and deep ultraviolet (110 nm to 400 nm) through resonant dispersive-wave emission.These results promise to be the foundation of a new generation of table-top light sources for ultrafast strong-field physics and advanced spectroscopy.

• The paper demonstrates soliton self-compression from 10 fs pulses to approximately 1.2 fs, achieving terawatt peak powers.
• It reports efficient resonant dispersive wave emission that generates tunable UV pulses (1–16 μJ) across a spectral range of 110–400 nm.
• The authors introduce scaling laws relating fibre core size to pulse dynamics, enabling multi-millijoule energy handling in large-core hollow capillary fibres.

High-Energy Pulse Self-Compression and Ultraviolet Generation in Hollow Capillary Fibres: A Technical Overview

In the paper titled "High-energy pulse self-compression and ultraviolet generation through soliton dynamics in hollow capillary fibres," the authors demonstrate significant advancements in the manipulation of optical solitons within gas-filled hollow capillary fibres (HCF). This work is crucial as it enables the scaling of soliton effects to multi-millijoule energies and terawatt peak powers, marking a substantial increase from prior techniques.

The authors outline the framework for leveraging optical soliton dynamics, which are well-documented in glass-core and microstructured fibres but have not been thoroughly explored in large-core HCF until now. By harnessing soliton effects under these conditions, they achieve soliton self-compression to sub-cycle pulses, which opens pathways for the generation of optical attosecond pulses. Furthermore, they demonstrate highly efficient resonant dispersive wave emission, which produces tunable high-energy pulses in the vacuum and deep ultraviolet range, spanning 110 nm to 400 nm.

Key Experimental Findings and Theoretical Developments

1. Soliton Self-Compression:
   • The paper successfully demonstrates soliton self-compression of 10 fs pulses to sub-femtosecond durations. This is significant given the peak power increase in comparison to previous experiments conducted in hollow-core photonic-crystal fibres (HC-PCF).
   • Numerical and experimental observations confirm compression down to 1.2 fs with resulting peak powers reaching the terawatt scale.
2. Resonant Dispersive Wave Emission:
   • The work reports the generation of ultraviolet pulses (1–16 μJ) by resonant dispersive-wave emission, verified using helium gas in the fibre.
   • The ultraviolet generation is continuous and tunable across a broad spectral range, surpassing the previously attainable energy levels and conversion efficiencies.
3. Scaling Laws and Practical Implications:
   • By introducing general scaling laws that relate the fibre core size to pulse dynamics, the authors provide a robust theoretical backbone for future research. These laws facilitate the transition from small cores (that have high loss but enable strong nonlinear effects) to large-core setups that allow the preservation of soliton characteristics at higher energies.
   • Comparisons with existing techniques, such as the use of small-core anti-resonant guiding fibres, highlight a potential energy increase of up to 1000 times.

Implications and Future Directions

The findings presented are expected to significantly advance ultrafast optics and photonics research. The demonstration of terawatt-level soliton compression opens new possibilities for generating optical attosecond pulses, which could surpass current capabilities in lightfield synthesizers. Additionally, the capability to produce high-energy, tunable ultraviolet pulses promises to furnish new tools for ultrafast spectroscopy and strong-field physics experiments.

The results suggest that further exploration into longer wavelengths and different gas mediums could yield a spectrum of new phenomena, augmenting the practical applications of soliton dynamics. The scalability demonstrated through manipulating fibre length and input pulse properties indicates that larger-core systems could push the boundaries of current laser systems, potentially achieving the practical feasibility of terawatt ultrafast light sources.

This research marks a milestone in optical fibre technology, augmenting the capabilities of current ultrafast pulse generation technologies. Future studies might explore the integration of these methods into existing industrial and scientific applications, broadening the utility and accessibility of such advanced light sources.