Observation of light-driven band structure via multiband high-harmonic spectroscopy

Intense light–matter interactions have revolutionized our ability to probe and manipulate quantum systems at sub-femtosecond timescales 1 , opening routes to the all-optical control of electronic currents in solids at petahertz rates 2 – 7 . Such control typically requires electric-field amplitudes...

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Bibliographic Details
Published in:Nature photonics 2022-06, Vol.16 (6), p.428-432
Main Authors: Uzan-Narovlansky, Ayelet J., Jiménez-Galán, Álvaro, Orenstein, Gal, Silva, Rui E. F., Arusi-Parpar, Talya, Shames, Sergei, Bruner, Barry D., Yan, Binghai, Smirnova, Olga, Ivanov, Misha, Dudovich, Nirit
Format: Article
Language:English
Subjects:
639/624/400/385
639/624/400/3923
Applied and Technical Physics
Band structure of solids
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Conduction bands
Crystal structure
Crystals
Electric fields
Energy gap
Harmonic generations
High-harmonic generation
Letter
Nonlinear optics
Optical control
Optical properties
Physics
Physics and Astronomy
Quantum Physics
Spectroscopy
Spectrum analysis
Voltage drop
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Summary:Intense light–matter interactions have revolutionized our ability to probe and manipulate quantum systems at sub-femtosecond timescales 1 , opening routes to the all-optical control of electronic currents in solids at petahertz rates 2 – 7 . Such control typically requires electric-field amplitudes in the range of almost volts per angstrom, when the voltage drop across a lattice site becomes comparable to the characteristic bandgap energies. In this regime, intense light–matter interaction induces notable modifications to the electronic and optical properties 8 – 10 , dramatically modifying the crystal band structure. Yet, identifying and characterizing such modifications remain an outstanding problem. As the oscillating electric field changes within the driving field’s cycle, does the band structure follow and how can it be defined? Here we address this fundamental question, proposing all-optical spectroscopy to probe the laser-induced closing of the bandgap between adjacent conduction bands. Our work reveals the link between nonlinear light–matter interactions in strongly driven crystals and the sub-cycle modifications in their effective band structure. Modifications of the effective band structure of MgO crystal is investigated on a timescale within one-quarter cycle of the electromagnetic-field oscillation. The high-harmonic generation spectra show a signature of laser-induced closing of the bandgap.
ISSN:1749-4885
1749-4893
DOI:10.1038/s41566-022-01010-1