Soliton self-compression in hollow capillary fibres

The creation of shorter and shorter optical pulses at higher and higher energies has been one of the primary aims of laser science and nonlinear optics. At high energies (few mJ), the dominant technique is currently the use of self-phase modulation (SPM) and self-steepening in a gas-filled hollow capillary fibre (HCF) to spectrally broaden pump pulses (typically ∼30 fs), followed by chirped mirrors to compensate the phase variation across the spectrum and hence achieve pulse compression [1]. In this way high-energy single-cycle pulses are routinely generated. An alternative route to shorter pulses is soliton self-compression, where the dispersion of the fibre is tuned to be anomalous such that it continuously compensates the phase of the pulse as its spectrum expands. This technique is widely established at low power in solid-core optical fibres and at few energies in hollow-core photonic-crystal fibres (HC-PCF) [2]. Here we experimentally demonstrate soliton self-compression in conventional gas-filled HCF at much higher energy [3]. We will describe how our technique opens the door to generating 1 fs, 1 TW optical pulses.