Generation and characterisation of terawatt-scale optical attosecond pulses, tunable DUV-VUV pulses, and single-cycle vector beams (Invited Paper)

We present XSOL, a new beamline for extreme soliton dynamics capable of generating terawatt-scale optical attosecond pulses and gigawatt-scale tunable vacuum-to-deep ultraviolet (VUV/DUV) pulses. Driven by 10 mJ, 40 fs pulses, the system utilizes gas-filled hollow-core fibres to achieve extreme pulse compression and frequency up-conversion. We report the generation of sub-cycle self-compressed pulses with ~1.3 fs duration and 2.1 mJ energy. We also demonstrate the generation of resonant dispersive waves tunable across the VUV/DUV range, achieving energies up to 170 µJ and durations of ~2.3 fs. Extending this platform, we also demonstrate the generation of single-cycle, millijoule-level radially polarised vector beams tunable down to 140 nm. These sources are fully characterised using advanced in-vacuum metrology, including TIPTOE for field-resolved measurements and transient-grating FROG employing new retrieval algorithms that incorporate dispersion effects. This work establishes a versatile, high-energy light source for next-generation strong-field physics.