scholarly journals Valley-selective optical Stark effect of exciton-polaritons in a monolayer semiconductor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Trevor LaMountain ◽  
Jovan Nelson ◽  
Erik J. Lenferink ◽  
Samuel H. Amsterdam ◽  
Akshay A. Murthy ◽  
...  
Keyword(s):  
High Speed ◽  
Stark Effect ◽  
Coherent Control ◽  
Energy Levels ◽  
Optical Methods ◽  
Transition Metal Dichalcogenide ◽  
Promising Alternative ◽  
Exciton Polaritons ◽  
Temperature Ranges ◽  
Optical Stark Effect

AbstractSelective breaking of degenerate energy levels is a well-known tool for coherent manipulation of spin states. Though most simply achieved with magnetic fields, polarization-sensitive optical methods provide high-speed alternatives. Exploiting the optical selection rules of transition metal dichalcogenide monolayers, the optical Stark effect allows for ultrafast manipulation of valley-coherent excitons. Compared to excitons in these materials, microcavity exciton-polaritons offer a promising alternative for valley manipulation, with longer lifetimes, enhanced valley coherence, and operation across wider temperature ranges. Here, we show valley-selective control of polariton energies in WS2 using the optical Stark effect, extending coherent valley manipulation to the hybrid light-matter regime. Ultrafast pump-probe measurements reveal polariton spectra with strong polarization contrast originating from valley-selective energy shifts. This demonstration of valley degeneracy breaking at picosecond timescales establishes a method for coherent control of valley phenomena in exciton-polaritons.

scholarly journals Valley-selective optical Stark effect of exciton-polaritons in a monolayer semiconductor

2020 ◽  
Author(s):  
Trevor LaMountain ◽  
Erik Lenferink ◽  
Samuel H. Amsterdam ◽  
Mark C. Hersam ◽  
Nathaniel P. Stern
Keyword(s):  
Stark Effect ◽  
Exciton Polaritons ◽  
Optical Stark Effect

ULTRAFAST MANIPULATION OF ELECTRON SPIN COHERENCE IN QUANTUM WELLS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 2930-2935 ◽  
Author(s):  
J. A. GUPTA ◽  
D. D. AWSCHALOM ◽  
R. KNOBEL ◽  
N. SAMARTH
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Energy Intensity ◽  
Coherent Control ◽  
Laser Pulses ◽  
Electron Spins ◽  
Spin Coherence ◽  
Ultrafast Laser Pulses ◽  
All Optical ◽  
Optical Stark Effect

A recently developed technique is reviewed with the potential for all-optical coherent control over electron spins in semiconductors. In these experiments, ultrafast laser pulses "tip" electron spins by generating effective magnetic fields via the optical Stark effect. Measurements of Stark shifts have provided estimates of the net tipping angle as a function of tipping pulse energy, intensity, and polarization. Background contributions to the measured tipping angle arise from the undesirable excitation of additional carriers by the tipping pulse.

scholarly journals Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

2021 ◽  
pp. 146808742110080
Author(s):  
Jamshid Malekmohammadi Nouri ◽  
Ioannis Vasilakos ◽  
Youyou Yan
Keyword(s):  
High Speed ◽  
Contact Point ◽  
Cylinder Liner ◽  
Optical Methods ◽  
Engine Management System ◽  
Great Success ◽  
Ic Engine ◽  
Contact Points ◽  
Lubricant Flow ◽  
Cavitation Intensity

A new engine block with optical access has been designed and manufactured capable of running up to 3000 r/min with the same specification as the unmodified engine. The optical window allowed access to the full length of the liner over a width of 25 mm to investigate the lubricant flow and cavitation at contact point between the rings and cylinder-liner. In addition, it allowed good access into the combustion chamber to allow charged flow, spray and combustion visualisation and measurements using different optical methods. New custom engine management system with build in LabView allowed for the precise full control of the engine. The design of the new optical engine was a great success in producing high quality images of lubricant flow, cavitation formation and development at contact point at different engine speeds ranging from 208 to 3000 r/min and lubricant temperatures (30°C–70°C) using a high-speed camera. The results under motorised operation confirmed that there was no cavitation at contact points during the intake/exhaust strokes due to low in-cylinder presure, while during compression/expansion strokes, with high in-cylinder pressure, considerable cavities were observed, in particular, during the compression stroke. Lubricant temperatures had the effect of promoting cavities both in their intensity and covered ring area up to 50°C as expected. Beyond that, although the cavitation intensity increases further with temperature, its area reduces due to possible collapse of the cavitating bubbles at higher temperature. The change of engine speed from 208 to 800 r/min increased cavitating area considerably by 52% of the ring area and was further increased by 19% at 1000 r/min. After that, the results showed very small increase in cavitation area (1.3% at 2000 r/min) with similar intensity and distribution across the ring.

Coupled Double Optical Stark Effect in CdSe Colloidal Nanoplatelets

ACS Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 745-751
Author(s):  
Dongmei Xiang ◽  
Yulu Li ◽  
Lifeng Wang ◽  
Yang Zhao ◽  
Kaifeng Wu
Keyword(s):  
Stark Effect ◽  
Optical Stark Effect

scholarly journals Magneto-Optical Stark Effect in Fe-Doped CdS Nanocrystals

Nano Letters ◽  
2021 ◽  
Author(s):  
Mahima Makkar ◽  
Lakshay Dheer ◽  
Anjali Singh ◽  
Luca Moretti ◽  
Margherita Maiuri ◽  
...  
Keyword(s):  
Stark Effect ◽  
Cds Nanocrystals ◽  
Optical Stark Effect

The Use of Modan 3D in Experimental Modal Analysis

2013 ◽  
Vol 486 ◽  
pp. 36-41 ◽  
Author(s):  
Róbert Huňady ◽  
František Trebuňa ◽  
Martin Hagara ◽  
Martin Schrötter
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
High Speed ◽  
Mechanical Vibration ◽  
Steel Sample ◽  
Experimental Modal Analysis ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Vibration Modes

Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

Theory of the Optical Stark Effect in Semiconductors

1988 ◽  
Vol 150 (2) ◽  
pp. 407-412 ◽  
Author(s):  
W. Schäfer ◽  
K.-H. Schuldt ◽  
R. Binder
Keyword(s):  
Stark Effect ◽  
Optical Stark Effect

High speed optical modulation in Ge quantum wells using quantum confined stark effect

2009 ◽  
Author(s):  
Yiwen Rong ◽  
Yangsi Ge ◽  
Yijie Huo ◽  
Marco Fiorentino ◽  
Theodore I. Kamins ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Speed ◽  
Stark Effect ◽  
Optical Modulation ◽  
Quantum Confined Stark Effect ◽  
Quantum Confined

Optical stark effect of excitons in semiconductors

1987 ◽  
Vol 38 (1-6) ◽  
pp. 235-238 ◽  
Author(s):  
D. Fröhlich ◽  
K. Reimann ◽  
R. Wille
Keyword(s):  
Stark Effect ◽  
Optical Stark Effect
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