Nanoscale control of high-harmonic generation
Plasmon enhanced high-harmonic generation from solids
Combining nano-scale patterning of surfaces with strong laser fields enable unprecedented capabilities at the intersection of nanophotonics and attosecond science. Our groundbreaking work aimed at enhancing the efficiency of high-harmonic emission with nanostructures.
Plasmonic antennas can enhance the intensity of a nanojoule laser pulse by localizing the electric field in their proximity. We use an array of monopole nano-antennas to demonstrate plasmon-assisted high-harmonic generation directly from the supporting crystalline silicon substrate. Despite the sparse coverage of antennas on the surface, and the small ~ 20 x 20 nm2 hotspots, harmonic emission is ten times brighter than without antennas, corresponding to a whopping ∼103 – 104 increase of high-harmonic emission density inside silicon. Imaging the high-harmonic radiation will allow nanometer and attosecond measurement of the plasmonic fieldthereby enabling more sensitive plasmon sensors while opening a new path to extreme-ultraviolet-frequency combs.
Tailored semiconductors as building blocks for high-harmonic optoelectronics
Three-dimensional structures confine the incident laser field into hotspots, too. We milled nanocones and nanogratings in Si and ZnO crystals, and demonstrated 10-fold enhancement of the emitted high-harmonic flux. We also integrate a Fresnel Zone plate on the Si surface by controlling the chemical doping with a focused ion beam, and demonstrate diffraction limited self-focusing of the emitted harmonics. Doing this in dielectrics might one day result in nanoscale focusing, for microscopy, laser-writing, and much more!