Abstract
Moderate efficiencies of nonlinear optical processes can be one of the challenges limiting even more widespread applications. Here we demonstrate a broadband and giant enhancement of nonlinear processes in ZnO through ultrafast permittivity engineering. A remarkable enhancement of the second and third harmonic generation of up to 2 orders of magnitude can be observed over a broadband range of driving wavelengths. Moreover, this nonlinearity enhancement is reversible with a recovery time of ∼120 fs. Additional experiments and simulations confirm that the observed enhancement originates from a permittivity change induced by the photocarrier population. Our results provide the opportunity to actively customize materials with a larger nonlinearity for nanophotonics on ultrafast time scales over broadband wavelength ranges. Utilizing this finding, we also demonstrate a relevant application, where a transient wave-guiding effect is induced by a donut-shaped photocarrier-excitation pulse, which both reduces the width of the spatial profile of harmonic emission below the diffraction limit and simultaneously increases its central emission strength.
Original language | English |
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Pages (from-to) | 5084-5090 |
Number of pages | 7 |
Journal | ACS Photonics |
Volume | 11 |
Issue number | 12 |
Early online date | 15 Nov 2024 |
DOIs | |
Publication status | Published - 18 Dec 2024 |
Bibliographical note
Publisher Copyright:© 2024 The Authors. Published by American Chemical Society.
Keywords
- epsilon near zero
- high harmonic generation
- microscopy
- Nonlinear optics
- permittivity engineering
- ultrafast modulation