High-energy soliton dynamics in hollow capillary fibres
Funded by: ERC
High-energy soliton dynamics in hollow capillary fibres for self-compression and deep and vacuum ultraviolet pulse generation
Optical soliton dynamics can cause the extreme alteration of the temporal and spectral shape of a propagating light pulse. They have been studied in optical fibres for over 50 years. Two of the most important soliton effects in ultrafast optics are soliton self-compression and resonant dispersive wave emission. The former leads to extreme compression of ultrafast laser pulses to single- or even sub-femtosecond duration—the generation of optical attosecond pulses—while the latter can create wavelength-tuneable few- to single-femtosecond pulses from the vacuum ultraviolet to the near infrared. In gas-filled microstructured fibres, these optical soliton dynamics occur at the megawatt to gigawatt peak power scale and the microjoule pulse energy level.
Starting with the formation of the group, and in the context of the ERC Starting Grant HISOL (High-energy Solitons) led by John Travers, we first demonstrated and subsequently developed the use of soliton dynamics in gas-filled hollow capillary fibres—essentially simple glass tubes. In comparison to microsctructured fibres, this allows for significant energy up-scaling to the multi-gigawatt to terawatt peak power and millijoule pulse energy regime. In addition, because hollow capillary fibres guide light across a huge bandwidth without interruptions due to guidance resonances, they allow for gapless tuneability of resonant dispersive waves across very large tuning ranges. These capabilities have led to numerous applications in ultrafast spectroscopy and imaging.
Soliton self-compression
In hollow capillary fibres, self-compression can create ~1.2-femtosecond pulses when driven at 800 nm and ~2-fs pulses when driven at 1800 nm, both with multi-gigawatt peak power. We are currently extending this concept in two directions:
- In our new XSOL beamline, funded by an ERC Consolidator Grant led by John Travers we further scale the process to the terawatt regime with the aim of driving relativistic nonlinear optics with uniquely short pulses.
- In the FASTER project, led by Christian Brahms, we are pushing the pulse duration to the attosecond regime for new applications in ultrafast spectroscopy.
Resonant dispersive wave emission
Resonant dispersive wave (RDW) emission is a consequence of nonlinear phase-matching between the self-compressed soliton and a linear (dispersive) wave in the fibre. This enables highly efficient nonlinear energy transfer to the phase-matched band, which usually lies at a much higher frequency (shorter wavelength) than the driving pulse. We have used this process to generate wavelength-tuneable pulses ranging from the vacuum ultraviolet (110 nm) to the near infrared (750 nm) with microjoule-level pulse energy and durations ranging from 1 to 3 fs.
 and [Brahms et al.](https://link.aps.org/doi/10.1103/PhysRevResearch.2.043037)](/project/hisol/dwave-01_hu_c53fe6200bb3e936.webp)
High-energy RDW emission fills a long-standing technology gap in advanced ultrafast spectroscopy, especially in the field of attochemistry, by enabling very fast resonant electronic excitation of molecules and other materials. For more information on the context and the specific advantages of the HISOL approach to generating few-femtosecond ultraviolet pulses, see our (now somewhat outdated) Perspective paper in APL Photonics.
HISOL, XSOL and FASTER are funded by the European Research Council under the European Union’s Horizon 2020 research and innovation programme, under ERC Starting Grant agreement HISOL, No. 679649, ERC Consolidator Grant agreement XSOL, No. 101001534, and ERC Starting Grant agreement FASTER, No. 101161675.
