Mid Term Review

High harmonic generation in the condensed matter phase

Mr David Freeman
Theoretical Physics, ANU

High harmonic generation (HHG) is a strongly non-linear light-matter interaction process, where atoms interacting with strong laser pulses emit high-order harmonics of the fundamental oscillating laser field. In gas targets, HHG is well studied as a tabletop source of coherent extreme ultraviolet (XUV) light useful for probing electron dynamics at its native timescale. It has also seen use in recent major industrial breakthroughs like XUV lithography, allowing the printing of near atomic size features on electronic wafers intended for circuitry. Despite its current success, XUV lithography using HHG in gas targets suffers from a major drawback: the HHG source doesn’t typically generate enough power to complete XUV scanning quickly and the laser input is expensive per chip produced.

The relatively weak return intensities for HHG considering gas targets and the possibility to probe electron dynamics in condensed matter have led to increased interest in understanding HHG for solid targets. Solid targets have been shown in recent literature to result in improved high harmonic returns across all energies and the formation of an extended harmonic plateau is drawing significant interest in the subject.

In this seminar I will review previous work on high harmonic generation considering plume Manganese, revealing: resonance enhancement in HHG, the tools required for analysing HHG in condensed matter, and the steps to be taken to model resonantly enhanced HHG considering a solid Manganese target. I will also present recent related work on HHG for Silicon, Diamond and Germanium targets at 2000nm and 800nm central wavelengths done in collaboration with colleagues from the University of Tsukuba, Japan.

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