Solid-state high-harmonic sources offer the possibility of compact, high-repetition-rate attosecond light emitters. However, the time structure of high harmonics must be characterized at the sub-cycle level. We use strong two-cycle laser pulses to directly control the time-dependent nonlinear current in single-crystal MgO, leading to the generation of extreme ultraviolet harmonics. We find that harmonics are delayed with respect to each other, yielding an atto-chirp, the value of which depends on the laser field strength. Our results provide the foundation for attosecond pulse metrology based on solid-state harmonics and a new approach to studying sub-cycle dynamics in solids.
Publication Source (Journal or Book title)
You, Y., Wu, M., Yin, Y., Chew, A., Ren, X., Gholam-Mirzaei, S., Browne, D., Chini, M., Chang, Z., Schafer, K., Gaarde, M., & Ghimire, S. (2017). Laser waveform control of extreme ultraviolet high harmonics from solids. Optics Letters, 42 (9), 1816-1819. https://doi.org/10.1364/OL.42.001816