Macroscopic effects of isolated-attosecond-pulse generation with a temporally asymmetric laser field

We present a theoretical investigation of an efficient method for generating macroscopic high-order harmonics with a smooth broadband continuous spectrum structure driven by a temporal asymmetric laser field. Our study demonstrates that selected continuous high-order harmonic spectra can support isolated attosecond pulses (IAPs) in the extreme ultraviolet region. Time-frequency analysis of high-order harmonics reveals that the smooth broadband continuous spectrum is dominated by long-trajectory electron emissions. The quantitative analysis of the phase mismatching reveals that the generation of the IAP is caused by the favorable transient phase matching of the long-trajectory electron emissions in the macroscopic medium, which can be attributed to the spatiotemporal reshaping of the laser waveform at high gas pressure. Furthermore, we also investigate the dependency of IAP on gas pressure and laser chirp parameters and find that the pulse width of the generated IAPs can be controlled by adjusting the gas pressure and the chirp parameters.

Automated summary

We propose an efficient method for generating macroscopic high-order harmonics with a smooth broadband continuous spectrum structure using a temporal asymmetric laser field. The study shows that the selected continuous high-order harmonic spectra can support isolated attosecond pulses in the extreme ultraviolet region. Analysis reveals that the smooth broadband continuous spectrum is dominated by long-trajectory electron emissions.