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Phoenix666 writes:

Scientists at the MPSD and CFEL have demonstrated the possibility of using a new knob to control and optimize the generation of high-order harmonics in bulk materials, one of the most important physical processes for generating high-energy photons and for the ultrafast manipulation of information.

The generation of high-order harmonics in gases is nowadays routinely used in many different areas of sciences, ranging from physics, to chemistry and biology. This strong-field phenomenon consists in converting many low-energy photons coming from a very strong laser, to fewer photons with a higher energy. Despite the growing interest in this phenomenon in solids, the mechanism behind the conversion of light is still under debate for solid materials.

[...] When atoms and molecules interact with strong laser pulses, they emit high-order harmonics of the fundamental driving laser field. The high-harmonic generation (HHG) in gases is regularly used nowadays to produce isolated attosecond pulses and coherent radiation ranging from visible to soft x-rays. Because of a higher electronic density, solids are one promising route towards compact, brighter HHG sources. However, their use is currently hampered by the lack of a microscopic understanding of the mechanism leading to HHG from solids.

*Sigh*, yes, Britons, we do know what "knob" means in your slang...

Nicolas Tancogne-Dejean et al, Ellipticity dependence of high-harmonic generation in solids originating from coupled intraband and interband dynamics, Nature Communications (2017). DOI: 10.1038/s41467-017-00764-5

Original Submission