Fig. 5: Ionization gate triggered by attosecond soliton.

a, A typical NPS measurement configuration without soliton generation when the fibre is removed. b, The measured electric field of the VIS–NIR pulse that is usually used as fibre input with an intensity envelope FWHM of 2.9 fs. c, The Fourier transform of the field shown in b together with the spectrum measured with a spectrometer. d, The reversed measurement configuration with fibre and rotated NPS sample to use the attosecond DUV–NIR beam as the injection pulse and the NIR beam as the drive. The DUV–NIR beam is strong enough to ionize argon via a two-photon or three-photon transition assuming the DUV drive contains the same measured photon energies as presented above. The FWHM pulse duration of the intensity envelope is 2.1 fs. e,f, The electric field measured in the reversed configuration (e) and its spectrum (f).