Near-resonant four-wave mixing of attosecond extreme-ultraviolet pulses with near-infrared pulses in neon: Detection of electronic coherences
- Author(s): Cao, Wei
- Warrick, Erika R
- Fidler, Ashley
- Leone, Stephen R
- Neumark, Daniel M
- et al.
Published Web Locationhttps://doi.org/10.1103/physreva.94.021802
© 2016 American Physical Society. Coherent narrow-band extreme-ultraviolet (EUV) light is generated by a near-resonant four-wave mixing (FWM) process between attosecond pulse trains and near-infrared pulses in neon gas. The near-resonant FWM process involves one vacuum-ultraviolet (VUV) photon and two near-infrared (NIR) photons and produces new higher-energy frequency components corresponding to the ns/nd to ground-state (2s22p6) transitions in the neon atom. The EUV emission exhibits small angular divergence (2 mrad) and monotonically increasing intensity over a pressure range of 0.5-16 Torr, suggesting phase matching in the production of the narrow-bandwidth coherent EUV light. In addition, time-resolved scans of the NIR nonlinear mixing process reveal the detection of a persistent, ultrafast bound electronic wave packet based on a coherent superposition initiated by the VUV pulse in the neon atoms. This FWM process using attosecond pulses offers a means for both efficient narrow-band EUV source generation and time-resolved investigations of ultrafast dynamics.