Surface High Harmonic Generation

Producing higher harmonics using surface plasmas

SHHG simulation

Image: Stefan Tietze

Surface high harmonics spectrum

Image: Matt Zepf

Coherent light is most easily generated using laser media with optical or infrared wavelengths. Coherent light – and especially with powerful femtosecond and attoscond pulses – is desirable in the extreme ultra-violet (XUV) and X-ray region also.

Transferring the successful techniques from conventional lasers is unfortunately not possible, due to the lack of transparent media and other technologies that have been developed in the optical region.

A highly successful avenue ist using non-linear media to convert optical lasers to XUV and X-rays using harmonic generation. We research converting the most powerful lasers such with TW to PW peak power using Relativistic Plasmas as a non-linear medium. The Relativistic Oscillating Mirror generated using such lasers employs the periodic Doppler motion to convert light from the optical to very high harmonic orders with 10 to 100s of times the frequency of the original laser.

Publications:

A. Blinne, S. Kuschel, S. Tietze, and M. Zepf, "Efficient retrieval of phase information from real-valued electromagnetic field dataExternal link," Journal of Computational Physics: X 1 (100019), (2019)
Y. Zhang, B. Qiao, X. Xu, H. Chang et al., "Intense attosecond pulses from laser-irradiated near-critical-density plasmas"External link, Opt. Express 25 (23), (2017)