Abstract-Enhanced spatial resolution of terahertz spectroscopy via semiconductor photoexcitation

 

Daniel Krotkov, Eli Flaxer, Sharly Fleischer, 

Experimental setup. In the EO sampling dashed rectangle, the components are a GaP crystal, a quarter waveplate, a Wollaston prism (WP) and two photodiodes (PD1 and PD2). The EO probe spatially unites with the THz via a pellicle beam splitter (PBS).

https://www.osapublishing.org/osac/fulltext.cfm?uri=osac-3-12-3365

We utilize the photoexcitation of a semiconductor material as a ‘reflectivity switch’ for a broadband terahertz field. We show that judicious use of this switch enables temporal characterization of the THz field with spatial resolution significantly surpassing the diffraction limit of the terahertz and provides desirable means for spatio-temporal terahertz spectroscopy.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Strong coupling of collective intermolecular vibrations in organic materials at terahertz frequencies

Ran Damari, Omri Weinberg, Daniel Krotkov, Natalia Demina, Katherine Akulov, Adina Golombek, Tal Schwartz, Sharly Fleischer,

α-Lactose molecules in a tunable THz cavity. a Chemical structure of α-lactose. b A microscope image of an α-lactose crystallite. c Absorption coefficient of the α-lactose pellet obtained from the THz absorption measurement. The inset shows the fit of the measured absorption peak (blue line) to a lorentzian line-shape (black dashed line). d A sketch of the open THz cavity used in the experiments

https://www.nature.com/articles/s41467-019-11130-y

Several years ago, strong coupling between electronic molecular transitions and photonic structures was shown to modify the electronic landscape of the molecules and affect their chemical behavior. Since then, this concept has evolved into a new field known as polaritonic chemistry. An important ingredient in the progress of this field was the demonstration of strong coupling with intra-molecular vibrations, which enabled the modification of processes occurring at the electronic ground-state. Here we demonstrate strong coupling with collective, inter-molecular vibrations occurring in organic materials in the low-terahertz region (≲$\lesssim$1012 Hz). Using a cavity filled with α-lactose molecules, we measure the temporal evolution and observe coherent Rabi oscillations, corresponding to a splitting of 68 GHz. These results take strong coupling into a new class of materials and processes, including skeletal polymer motions, protein dynamics, metal organic frameworks and other materials, in which collective, spatially extended degrees of freedom participate in the dynamics.

Abstract-Strong Coupling of Light with Collective Terahertz Vibrations in Organic Materials

Ran Damari, Omri Weinberg, Natalia Demina, Katherine Akulov, Daniel Krotkov, Sharly Fleischer, and Tal Schwartz

https://www.osapublishing.org/abstract.cfm?uri=CLEO_QELS-2019-FM3D.8

We demonstrate for the first time strong coupling between a terahertz cavity and collective, intermolecular vibrations in organic crystals. Beyond observing the Rabi splitting, we directly measure the vacuum Rabi oscillations using time domain THz spectroscopy.

© 2019 The Author(s)