Qiushuo Sun ; Xudong Liu ; Jie Cao ; Rayko Stantchev ...

1 Monday, September 10, 2018. Shirotori 09:30 - 10:00 Opening Remarks Hall Session Type: Others Shirotori 10:00 - 11:30 Mo-A1-S Plenary Session Hall Session Type: Plenary Chair: Daniel Mittleman Mo-A1-S- 10:00 THz Aqueous Photonics And Beyond 1. Qi Jin1; Yiwen E1; Liangliang Zhang2; Cunlin Zhang2; Anton Tcypkin3; Sergey Kozlov3; Xi-Cheng Zhang1. 1 University of Rochester, United States; 2 Capital Normal University, China; 3 ITMO. University, Russian Federation Three of four states of matter: solid, gas, and plasma have been used for THz wave generation for decades. However, the demonstration of THz wave generation from liquid sources was conspicuously absent, especially from liquid water, due to its infamously strong absorption characteristics in the THz regime.

2 Liquids have a high molecular density and a relatively low ionization threshold, meaning that light over a certain area will interact with many more molecules than an equivalent cross- section of gases and will generate more electrons. This makes liquids potential candidates for the generation of THz waves. Mo-A1-S- 10:45 The Long Journey From Far-infrared To THz 2. Qing Hu MIT, United States In this Button Prize speech, the author will review the long journey, spanning over his entire research career, from far-infrared to THz. Shirotori 12:30 - 14:00 Mo-P1-R1 Spectroscopy and Material Properties I. Hall Session Type: Oral Chair: Frank Hegmann Mo-P1- 12:30 [Keynote] Terahertz Spectroscopy Of 2D Materials R1-1.

3 Lyubov Titova1; Guangjiang Li1; Kateryna Kushnir2; Mengjing Wang3; Yongchang Dong4; Kristie Koski5; Ramakrishna Podila4. 1 Worcester Polytechnic Institute, United States; 2 Worcester Polytechnic Insitute, United States; 3 Brown University, United States; 4 Clemson University, United States; 5 University of California Davis, United States We use time-resolved THz spectroscopy to study the e ects of photoexcitation on conductivity and ultrafast carrier in 2D layered materials with di erent electronic properties: metallic transition metal carbides (MXenes) and semiconducting germanium sul de (GeS). Mo-P1- 13:00 Changed Graphene THz Conductivity Mapping Under E-beam Excitation R1-2.

4 Xiaodong Feng; Zhuocheng Zhang; Sen Gong; Min Hu; Jun Zhou; Shenggang Liu University of Electronic Science and Technology of China, China Based on terahertz (THz) time-domain spectroscopy, the e ects of a 100 eV. electron beam (e-beam) excitation ongraphene THz conductivity are presented. The results indicate that a 100 eV e-beam excitation induces a decrease in THz conductivity of graphene, interpreted as electron doping in graphene from the interaction of the e-beam with graphene resulting in the decrease in hole concentration as the graphene is initially p-type doping. Besides, through two- dimensional scanning of graphene by THz spectra without and with e-beam irradiation, the in situ mapping image of changed graphene THz conductivity is obtained, showing carrier transport process in graphene.

5 The ndings are of signi cance for understanding the carrier transport in graphene under e-beam irradiation and for the development of THz electronic devices based on graphene. Mo-P1- 13:15 Probing Photo-induced Vibrational Kinetics In Perovskite Thin Films R1-3. Qiushuo Sun1; Xudong Liu1; Jie Cao1; Rayko Stantchev1; Yang Zhou1; Xuequan Chen1; Edward Parrott1; Ni Zhao1; Emma MacPherson2. 1 The Chinese University of Hong Kong, Hong Kong; 2 University of Warwick, United Kingdom Subwavelength perovskite thin lms can only cause less than a 10% intensity reduction of the transmitted terahertz (THz) signal; this small dynamic range makes it di cult to track minor changes in the phonon modes.

6 We propose a THz thin lm total internal re ection (TF-TIR) spectroscopy technique to characterize photo- induced spectral changes of MAPbI3, , MAPbI2Br1 and MAPbBr3. Our approach enhanced the THz responsivity of the perovskites thin lms by a factor of 4 compared to THz transmission spectroscopy. The light induced the strength of the phonon modes at around 2 THz to increase after 5 min of illumination, corresponding to the enhanced stretching of the lead halide bond. After 10 min, the strength of the phonon modes at around 1 THz started to decrease, corresponding to the weakened bending of the lead halide bond. Blue shifts were observed on the resonant frequencies apart from MAPbBr3.

7 By comparing the results of four perovskites, we conclude the perovskites that have higher iodide ratio are more unstable in the presence of light and moisture. With the support of X-ray di raction measurements, we suggest that THz TF-TIR spectroscopy provides distinct information of vibrational kinetics of lead-halide bond in perovskites. [Keynote] Strong Terahertz Plasmonic Resonances In Thin- lm Cd3As2: A Mo-P1- 13:30. Three-dimensional Dirac Semimetal R1-4. Ashish Chanana; Berardi-Sensale Rodriguez; Prashnath R Gopalan University of Utah, United States Abstract-- Linear dispersion of energy band-diagram in Dirac semimetals has been associated with strong plasmon coupling in terahertz regime.

8 Graphene, in this regard, has been projected to play crucial role in terahertz optoelectronics due to high carrier mobility and conductivity. However, in the realm of quantum materials, a three-dimension analogue of graphene, Cd3As2, so called 3D semimetal, has been shown to have carrier mobility and fermi-velocity well exceeding that in graphene. We experimentally demonstrate synthesis of high-quality large-area Cd3As2 thin- lms and realization of THz plasmonic structures. The structures exhibit quality factor ~5, at frequency of ~ THz, the highest reported to-date at room temperature in any semiconductor or semimetal. Our results evidence that the 3D nature of Cd3As2 provides for a more robust platform for terahertz applications than what is otherwise possible in graphene.

9 Room 12:30 - 14:00 Mo-P1-1b High-Field THz Wave Generation and Nonlinear THz Physics I. 131+132. Session Type: Oral Chair: Peter Uhd Jepsen [Keynote] Terahertz Quasiparticle Acceleration: From Electron--Hole Mo-P1- 12:30. Collisions To Lightwave Valleytronics 1b-1. Fabian Langer1; Christoph P. Schmid1; Stefan Schlauderer1; Philipp Nagler1;. Christian Sch ller1; Tobias Korn1; Martin Gmitra1; Jaroslav Fabian1; Peter G. Hawkins2; Johannes T. Steiner2; Ulrich Huttner2; Stephan W. Koch2; Mackillo Kira3;. Rupert Huber1. 1 University of Regensburg, Germany; 2 University of Marburg, Germany; 3 University of Michigan, United States Intense lightwaves can accelerate quasiparticles inside solids.

10 This strong- eld light- matter interaction results in the emission of high-harmonic or high-order sideband radiation. While the former process relies on a complex coupling between simultaneously driven interband polarization and intraband currents, high-order sidebands originate from a ballistic acceleration of the quasiparticles within the bands. This mechanism allows for the implementation of a quasiparticle collider in order to study those entities in close analogy to conventional collision experiments. Accelerating electrons and holes in a monolayer of transition metal dichalcogenides extends this scheme to internal quantum degrees of freedom.