scholarly journals BaTiO3 based photonic time crystal and momentum stop band

2020 ◽  
Vol 557 (1) ◽  
pp. 105-111
Author(s):  
Zafer Ozer ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay
Keyword(s):  
Photonic Crystals ◽  
Stop Band ◽  
Band Gaps ◽  
Topological Phase ◽  
Forbidden Regions ◽  
Nonlinear Harmonic Generation ◽  
Energy And Momentum ◽  
Topological Phase Transitions ◽  
Photonic Energy ◽  
Time Crystals

Temporally periodic photonic crystals develop an ω-k dispersion relation with momentum band gaps. While conventional photonic crystals induce forbidden bands in the frequency spectrum of photons, photonic time crystals create forbidden regions in the momentum spectrum of photons. This effect allows for enhanced control over many optical processes that require both photonic energy and momentum conservations such as nonlinear harmonic generation. The simulation results show that more intensive scatter fields can obtained in photonic space time crystal. Also, we investigate topological phase transitions of photonic time crystals systems.

Effect of Double Defects on Transmission Spectra of One-Dimensional Photonic Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 725-728 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai ◽  
Yun Gao Cai
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Theoretical Calculations ◽  
Stop Band ◽  
Band Gaps ◽  
Characteristic Matrix ◽  
Frequency Range ◽  
Defect Band ◽  
One Dimensional ◽  
The One

Considered the model of the one-dimensional photonic crystals (1-D PCs) with double defects, the refractive indexes (n2’, n3’ and n2’’, n3’’) of the double defects were 2.0, 4.0 and 4.0, 2.0 respectively. With parameter n2=1.5, n3=2.5, by theoretical calculations with characteristic matrix method, the results shown that for a certain number (14 was taken) of layers of the 1-D PCs, when the double defects abutted, there was a defect band gap in the stop band gap, while when the double defects separated, there occurred two defect band gaps in the stop band gap; besides, with the separation of the two defects, the transmittance of the double defect band gaps decreased gradually. In addition, in this progress, the frequency range of the stop band gap has a little increase from 0.092 to 0.095.

scholarly journals Creating polar antivortex in PbTiO3/SrTiO3 superlattice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adeel Y. Abid ◽  
Yuanwei Sun ◽  
Xu Hou ◽  
Congbing Tan ◽  
Xiangli Zhong ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Phase Field ◽  
Driving Force ◽  
Topological Phase ◽  
Phase Field Simulation ◽  
Topological Structures ◽  
Field Simulation ◽  
Condensed Matters ◽  
Topological Phase Transitions ◽  
Insight Into

AbstractNontrivial topological structures offer a rich playground in condensed matters and promise alternative device configurations for post-Moore electronics. While recently a number of polar topologies have been discovered in confined ferroelectric PbTiO3 within artificially engineered PbTiO3/SrTiO3 superlattices, little attention was paid to possible topological polar structures in SrTiO3. Here we successfully create previously unrealized polar antivortices within the SrTiO3 of PbTiO3/SrTiO3 superlattices, accomplished by carefully engineering their thicknesses guided by phase-field simulation. Field- and thermal-induced Kosterlitz–Thouless-like topological phase transitions have also been demonstrated, and it was discovered that the driving force for antivortex formation is electrostatic instead of elastic. This work completes an important missing link in polar topologies, expands the reaches of topological structures, and offers insight into searching and manipulating polar textures.

scholarly journals Interaction-driven topological phase transitions in fermionic SU(3) systems

2020 ◽  
Vol 101 (24) ◽  
Author(s):  
Mohsen Hafez-Torbati ◽  
Jun-Hui Zheng ◽  
Bernhard Irsigler ◽  
Walter Hofstetter
Keyword(s):  
Phase Transitions ◽  
Topological Phase ◽  
Topological Phase Transitions
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