Tunable exciton-polaritons emerging from WS2 monolayer excitons in a photonic lattice at room temperature

AbstractEngineering non-linear hybrid light-matter states in tailored lattices is a central research strategy for the simulation of complex Hamiltonians. Excitons in atomically thin crystals are an ideal active medium for such purposes, since they couple strongly with light and bear the potential to harness giant non-linearities and interactions while presenting a simple sample-processing and room temperature operability. We demonstrate lattice polaritons, based on an open, high-quality optical cavity, with an imprinted photonic lattice strongly coupled to excitons in a WS2 monolayer. We experimentally observe the emergence of the canonical band-structure of particles in a one-dimensional lattice at room temperature, and demonstrate frequency reconfigurability over a spectral window exceeding 85 meV, as well as the systematic variation of the nearest-neighbour coupling, reflected by a tunability in the bandwidth of the p-band polaritons by 7 meV. The technology presented in this work is a critical demonstration towards reconfigurable photonic emulators operated with non-linear photonic fluids, offering a simple experimental implementation and working at ambient conditions.

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Optical switching of topological phase in a perovskite polariton lattice

Science Advances ◽

10.1126/sciadv.abf8049 ◽

2021 ◽

Vol 7 (21) ◽

pp. eabf8049

Author(s):

Rui Su ◽

Sanjib Ghosh ◽

Timothy C. H. Liew ◽

Qihua Xiong

Keyword(s):

Optical Switching ◽

Room Temperature ◽

Optical Pumping ◽

Optical Nonlinearity ◽

Edge States ◽

Ambient Conditions ◽

Strong Light ◽

Exciton Polaritons ◽

Matter Interaction ◽

Light Matter Interaction

Strong light-matter interaction enriches topological photonics by dressing light with matter, which provides the possibility to realize active nonlinear topological devices with immunity to defects. Topological exciton polaritons—half-light, half-matter quasiparticles with giant optical nonlinearity—represent a unique platform for active topological photonics. Previous demonstrations of exciton polariton topological insulators demand cryogenic temperatures, and their topological properties are usually fixed. Here, we experimentally demonstrate a room temperature exciton polariton topological insulator in a perovskite zigzag lattice. Polarization serves as a degree of freedom to switch between distinct topological phases, and the topologically nontrivial polariton edge states persist in the presence of onsite energy perturbations, showing strong immunity to disorder. We further demonstrate exciton polariton condensation into the topological edge states under optical pumping. These results provide an ideal platform for realizing active topological polaritonic devices working at ambient conditions, which can find important applications in topological lasers, optical modulation, and switching.

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Motional narrowing, ballistic transport, and trapping of room-temperature exciton polaritons in an atomically-thin semiconductor

Nature Communications ◽

10.1038/s41467-021-25656-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

M. Wurdack ◽

E. Estrecho ◽

S. Todd ◽

T. Yun ◽

M. Pieczarka ◽

...

Keyword(s):

Room Temperature ◽

Ballistic Transport ◽

Partial Coherence ◽

Great Promise ◽

Transition Metal Dichalcogenide ◽

Ambient Conditions ◽

Electron Hole ◽

Exciton Polaritons ◽

Motional Narrowing ◽

Potential Landscape

AbstractMonolayer transition metal dichalcogenide crystals (TMDCs) hold great promise for semiconductor optoelectronics because their bound electron-hole pairs (excitons) are stable at room temperature and interact strongly with light. When TMDCs are embedded in an optical microcavity, excitons can hybridise with cavity photons to form exciton polaritons, which inherit useful properties from their constituents. The ability to manipulate and trap polaritons on a microchip is critical for applications. Here, we create a non-trivial potential landscape for polaritons in monolayer WS2, and demonstrate their trapping and ballistic propagation across tens of micrometers. We show that the effects of dielectric disorder, which restrict the diffusion of WS2 excitons and broaden their spectral resonance, are dramatically reduced for polaritons, leading to motional narrowing and preserved partial coherence. Linewidth narrowing and coherence are further enhanced in the trap. Our results demonstrate the possibility of long-range dissipationless transport and efficient trapping of TMDC polaritons in ambient conditions.

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Strong Coupling: Polariton Bose Condensation

10.1093/oso/9780198782995.003.0008 ◽

2017 ◽

Author(s):

Alexey V. Kavokin ◽

Jeremy J. Baumberg ◽

Guillaume Malpuech ◽

Fabrice P. Laussy

Keyword(s):

Strong Coupling ◽

Room Temperature ◽

Elevated Temperatures ◽

Dissipative System ◽

Bose Condensation ◽

Einstein Condensation ◽

Strong Coupling Regime ◽

Stimulated Scattering ◽

Exciton Polaritons ◽

Bose Einstein

In this Chapter we address the physics of Bose-Einstein condensation and its implications to a driven-dissipative system such as the polariton laser. We discuss the dynamics of exciton-polaritons non-resonantly pumped within a microcavity in the strong coupling regime. It is shown how the stimulated scattering of exciton-polaritons leads to formation of bosonic condensates that may be stable at elevated temperatures, including room temperature.

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Visible-light-initiated Catalyst-free Oxidative Cleavage of Triaryl-Substituted Alkenes C=C Bonds under Ambient Conditions

Green Chemistry ◽

10.1039/d1gc00716e ◽

2021 ◽

Author(s):

Wenjing Li ◽

Shun Li ◽

Lihua Luo ◽

Yichen Ge ◽

Jiaqi Xu ◽

...

Keyword(s):

Visible Light ◽

Room Temperature ◽

Ambient Air ◽

Oxidative Cleavage ◽

Ambient Conditions ◽

Blue Led ◽

Catalyst Free

The catalyst-free oxidative cleavage of (Z)-triaryl-substituted alkenes bearing pyridyl motif with ambient air under irradiation of blue LED at room temperature has been developed. The reaction was facile and scalable,...

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Foldable and washable textile-based OLEDs with a multi-functional near-room-temperature encapsulation layer for smart e-textiles

npj Flexible Electronics ◽

10.1038/s41528-021-00112-0 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

So Yeong Jeong ◽

Hye Rin Shim ◽

Yunha Na ◽

Ki Suk Kang ◽

Yongmin Jeon ◽

...

Keyword(s):

Room Temperature ◽

Wearable Electronics ◽

Ambient Conditions ◽

Light Emitting ◽

Stable Operating ◽

Mechanical Durability ◽

Potential Applications ◽

Wearable Electronic ◽

Data Signal ◽

Wearable Electronic Devices

AbstractWearable electronic devices are being developed because of their wide potential applications and user convenience. Among them, wearable organic light emitting diodes (OLEDs) play an important role in visualizing the data signal processed in wearable electronics to humans. In this study, textile-based OLEDs were fabricated and their practical utility was demonstrated. The textile-based OLEDs exhibited a stable operating lifetime under ambient conditions, enough mechanical durability to endure the deformation by the movement of humans, and washability for maintaining its optoelectronic properties even in water condition such as rain, sweat, or washing. In this study, the main technology used to realize this textile-based OLED was multi-functional near-room-temperature encapsulation. The outstanding impermeability of TiO2 film deposited at near-room-temperature was demonstrated. The internal residual stress in the encapsulation layer was controlled, and the device was capped by highly cross-linked hydrophobic polymer film, providing a highly impermeable, mechanically flexible, and waterproof encapsulation.

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A machine-learning-based alloy design platform that enables both forward and inverse predictions for thermo-mechanically controlled processed (TMCP) steel alloys

Scientific Reports ◽

10.1038/s41598-021-90237-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jin-Woong Lee ◽

Chaewon Park ◽

Byung Do Lee ◽

Joonseo Park ◽

Nam Hoon Goo ◽

...

Keyword(s):

Machine Learning ◽

Feature Space ◽

Research Strategy ◽

Nsga Ii ◽

Steel Alloys ◽

Non Linear ◽

Data Driven Approach ◽

Processing Information ◽

Set Up ◽

World Industry

AbstractPredicting mechanical properties such as yield strength (YS) and ultimate tensile strength (UTS) is an intricate undertaking in practice, notwithstanding a plethora of well-established theoretical and empirical models. A data-driven approach should be a fundamental exercise when making YS/UTS predictions. For this study, we collected 16 descriptors (attributes) that implicate the compositional and processing information and the corresponding YS/UTS values for 5473 thermo-mechanically controlled processed (TMCP) steel alloys. We set up an integrated machine-learning (ML) platform consisting of 16 ML algorithms to predict the YS/UTS based on the descriptors. The integrated ML platform involved regularization-based linear regression algorithms, ensemble ML algorithms, and some non-linear ML algorithms. Despite the dirty nature of most real-world industry data, we obtained acceptable holdout dataset test results such as R2 > 0.6 and MSE < 0.01 for seven non-linear ML algorithms. The seven fully trained non-linear ML models were used for the ensuing ‘inverse design (prediction)’ based on an elitist-reinforced, non-dominated sorting genetic algorithm (NSGA-II). The NSGA-II enabled us to predict solutions that exhibit desirable YS/UTS values for each ML algorithm. In addition, the NSGA-II-driven solutions in the 16-dimensional input feature space were visualized using holographic research strategy (HRS) in order to systematically compare and analyze the inverse-predicted solutions for each ML algorithm.

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Luminescence from Droplet-Etched GaAs Quantum Dots at and Close to Room Temperature

Nanomaterials ◽

10.3390/nano11030690 ◽

2021 ◽

Vol 11 (3) ◽

pp. 690

Author(s):

Leonardo Ranasinghe ◽

Christian Heyn ◽

Kristian Deneke ◽

Michael Zocher ◽

Roman Korneev ◽

...

Keyword(s):

Quantum Dots ◽

Penetration Depth ◽

Gaas Substrate ◽

Room Temperature ◽

Green Laser ◽

Significant Loss ◽

Blue Laser ◽

Ambient Conditions ◽

Thermal Escape ◽

Intensity Loss

Epitaxially grown quantum dots (QDs) are established as quantum emitters for quantum information technology, but their operation under ambient conditions remains a challenge. Therefore, we study photoluminescence (PL) emission at and close to room temperature from self-assembled strain-free GaAs quantum dots (QDs) in refilled AlGaAs nanoholes on (001)GaAs substrate. Two major obstacles for room temperature operation are observed. The first is a strong radiative background from the GaAs substrate and the second a significant loss of intensity by more than four orders of magnitude between liquid helium and room temperature. We discuss results obtained on three different sample designs and two excitation wavelengths. The PL measurements are performed at room temperature and at T = 200 K, which is obtained using an inexpensive thermoelectric cooler. An optimized sample with an AlGaAs barrier layer thicker than the penetration depth of the exciting green laser light (532 nm) demonstrates clear QD peaks already at room temperature. Samples with thin AlGaAs layers show room temperature emission from the QDs when a blue laser (405 nm) with a reduced optical penetration depth is used for excitation. A model and a fit to the experimental behavior identify dissociation of excitons in the barrier below T = 100 K and thermal escape of excitons from QDs above T = 160 K as the central processes causing PL-intensity loss.

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Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer

Nature Communications ◽

10.1038/ncomms13328 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 104

Author(s):

Nils Lundt ◽

Sebastian Klembt ◽

Evgeniia Cherotchenko ◽

Simon Betzold ◽

Oliver Iff ◽

...

Keyword(s):

Room Temperature ◽

Exciton Polaritons

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Heat Transfer Analysis of Room-Temperature Finned-Tube Evaporator for Cryogenic Nitrogen

Journal of Heat Transfer ◽

10.1115/1.4003924 ◽

2011 ◽

Vol 133 (9) ◽

Cited By ~ 1

Author(s):

Shun Ching Lee ◽

Tzu-Min Chen

Keyword(s):

Heat Flux ◽

Room Temperature ◽

Integrated Model ◽

Finned Tube ◽

Heat Transfer Analysis ◽

Outlet Temperature ◽

Ambient Conditions ◽

Governing Equations ◽

Initial Value ◽

Two Phase

Abstract The behavior of cryogenic nitrogen in a room-temperature evaporator six meters long is analyzed. Trapezoid fins are employed to enhance the heat flux supplied by the environment. The steady-state governing equations specified by the mixed parameters are derived from the conservations of momentum and energy. The initial value problem is solved by space integration. The fixed ambient conditions are confirmed by way of the meltback effect. An integrated model is utilized to analyze the convective effect of two-phase flow, which dominates the evaporation behavior. Another integrated model is employed to determine the total heat flux from the environment to the wet surface of the evaporator. The foundation of the formation of an ice layer surrounding the evaporator is presented. If the fin height is shorter than 0.5 m, the whole evaporator is surrounded by ice layer. If the fin height is longer than 0.5 m, the total pressure drop of nitrogen in the tube is negligible. The outlet temperature is always within the range between −12 °C and 16 °C for the evaporator with the fin height of 1.0 m. For the evaporator with dry surface, the nitrogen has the outlet temperature less than the ambient temperature at least by 5 °C.

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