High-harmonic spectroscopy is an all-optical nonlinear technique with inherent attosecond temporal resolution. It has been applied to a variety of systems in the gas phase and solid state. Here we extend its use to liquid samples. By studying high-harmonic generation over a broad range of wavelengths and intensities, we show that the cut-off energy is independent of the wavelength beyond a threshold intensity and that it is a characteristic property of the studied liquid. We explain these observations with a semi-classical model based on electron trajectories that are limited by the
electron scattering. This is further confirmed by measurements performed with elliptically polarized light and with ab-initio time-dependent density functional theory calculations. Our results propose high-harmonic spectroscopy as an all-optical approach for determining the effective mean free paths of slow electrons in liquids.
The fundamental opto-electronic properties of two-dimensional (2D) materials can be tailored based on their nanoscale charge environment. Charge transfer at the interface of two atomically-thin layers offers a route to nanoscale charge modulation at the smallest possible length scales. In our study, we exploit this behavior to achieve nanoscale control of charge-transfer plasmon-polaritons (CPPs) and phonon-polaritons (PhPs) in graphene/α-RuCl3 and hBN/α-RuCl3 heterostructures, respectively. Using infrared near-field optical microscopy, we directly observe CPPs and PhPs, revealing emergent charge doping and optical conductivity at these novel 2D interfaces. Our results validate charge-transfer interfaces as tunable platforms for confined light.
Select quantum materials can support polaritons, hybrid light matter waves, with sub-diffraction-limited confinement. In this talk I will overview recent progress on polaritons in hyperbolic materials, which propagate as conical rays throughout the bulk of these crystals. I will discuss polaritons in a class of hyperbolic hetero-bicrystals. Our data reveals negative refraction, spectral gaps and wave localization can occur in these systems.
Excitons, quasi-particles generated by the Coulomb interaction between an excited electron and a hole, have been proposed as a possibility to overcome the limits of electronics. To fully exploit them, a deeper understanding of their interaction with light is required. In this study, the interaction of a core exciton with an intense, few-femtosecond infrared pulse is investigated with attosecond transient reflection spectroscopy in a bulk monocrystalline MgF2 sample. The distinct few- and sub-femtosecond optical responses attest the dual, atomic- and solid-like, nature of core excitons. Sub-femtosecond dynamics, in particular, are dictated by the interplay between the exciton and the conduction band of the crystal. Theoretical simulations allow to propose the exciton binding energy as a lever to control exciton dynamics on an ultrafast timescale.
This Conference Presentation, “Programmable hyperbolic polaritons in van der Waals semiconductors,” was recorded for the Photonics West 2021 Digital Forum.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.