Dynamical birefringence: Electron-hole recollisions as probes of Berry curvature

Abstract

The direct measurement of Berry phases is still a great challenge in condensed matter systems. The bottleneck has been the ability to adiabatically drive an electron coherently across a large portion of the Brillouin zone in a solid where the scattering is strong and complicated. We break through this bottleneck and show that high-order sideband generation (HSG) in semiconductors is intimately affected by Berry phases. Electron-hole recollisions and HSG occur when a near-band gap laser beam excites a semiconductor that is driven by sufficiently strong terahertz (THz)-frequency electric fields. We carried out experimental and theoretical studies of HSG from three GaAs/AlGaAs quantum wells. The observed HSG spectra contain sidebands up to the 90th order, to our knowledge the highest-order optical nonlinearity observed in solids. The highest-order sidebands are associated with electron-hole pairs driven coherently across roughly 10% of the Brillouin zone around the Γpoint. The principal experimental claim is a dynamical birefringence: the sidebands, when the order is high enough (> 20), are usually stronger when the exciting near-infrared (NIR) and the THz electric fields are polarized perpendicular than parallel; the sideband intensities depend on the angles between the THz field and the crystal axes in samples with sufficiently weak quenched disorder; and the sidebands exhibit significant ellipticity that increases with increasing sideband order, despite nearly linear excitation and driving fields. We explain dynamical birefringence by generalizing the three-step model for high order harmonic generation. The hole accumulates Berry phases due to variation of its internal state as the quasi-momentum changes under the THz field. Dynamical birefringence arises from quantum interference between time-reversed pairs of electron-hole recollision pathways.

References in corpus (5)

• Dissipationless Quantum Spin Current at Room Temperature
• High harmonic generation from Bloch electrons in solids
• Strong-Field Perspective on High-Harmonic Radiation from Bulk Solids
• The Effect of Multiple Conduction Bands on High Harmonic Emission from Dielectrics
• Nonlinear optical response induced by non-Abelian Berry curvature in time-reversal-invariant insulators

Cited by in corpus (6)

• Generation of Circularly-Polarised High-Harmonics with Identical Helicity in Two-Dimensional Materials
• Probing phonon-driven symmetry alterations in graphene via high-harmonic spectroscopy
• Probing dephasing time of crystals via spectral properties of high-harmonic generation
• Orientation-dependent transition rule in high-order harmonic generation from solids
• An explicit formula for high-order sideband polarization by extreme tailoring of Feynman path integrals
• Multiple plateaus of high-sideband generation from Floquet matters