Topological Photonic Crystals: Physics, Designs, and Applications

Tang, Guojing; He, Xin‐Tao; Shi, Fu‐Long; Liu, Jian‐Wei; Chen, Xiao‐Dong; Dong, Jian‐Wen

doi:10.1002/lpor.202100300

Cited by 190 publications

(70 citation statements)

References 418 publications

(846 reference statements)

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“…The topological invariant of the VPC is defined as the valley Chern number, C V = C K −C K , where C K is the integral of Berry curvature around K point [4]. Further, we calculate the Berry curvature of the DPC, as shown in Fig.…”

Section: Valley Photonic Crystalsmentioning

confidence: 99%

On/Off Switching of Valley Topological Edge States in the Terahertz Region

Ouyang

et al. 2022

IEEE Photonics J.

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Topological photonic devices provide a powerful platform to control the flow of light because their topologically protected edge states can be immune to backscattering and be robust to impurities, disorders, and defects. As one of the topological photonic systems, valley photonic crystals have attracted great attention because they can achieve a large bandgap and be easily combined with modern micro-nano fabrication technology. Terahertz photonic devices are of enormous interest in next-generation communications. Here, we design a valley photonic crystal consisting of a triangular lattice with three metal rod scatterers. By rotating the three metal rods in opposite directions to break the inversion symmetry, we achieve a bandgap width of up to 70% and observe the transport of the edge states in the terahertz region. By replacing part of the structure with phase change material VO 2 , on/off switching of the terahertz photonic topological edge states is realized, and the attenuation can be also modeled by adjusting the size of the VO 2 region. The proposed regime has potential applications in sensing and 6G communications.

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Section: Valley Photonic Crystalsmentioning

confidence: 99%

On/Off Switching of Valley Topological Edge States in the Terahertz Region

Ouyang

et al. 2022

IEEE Photonics J.

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Section: Introductionmentioning

confidence: 99%

“…In recent years, there has been an increasing interest in topological photonics which supports unidirectional electromagnetic wave propagation and show robustness against backscattering, disorders, and defects [ 1 , 2 , 3 , 4 , 5 ]. Researchers have found that one-way edge modes can appear in valley PCs and magneto-optical photonic crystals (MOPCs) [ 2 , 3 , 4 ]. Among them, MOPCs provide an important platform for studying the generation and transport properties of topological photonic states (TPSs) by breaking time-reversal symmetry via a dc external magnetic field (EMF), which can be seen as a one-way mode [ 6 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Reversible Conversion of Odd/Even One-Way Modes in Magneto-Optical Photonic Crystal Double-Channel Waveguides

Zhuang

Chen

et al. 2022

Nanomaterials

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We have studied the transmission properties of odd/even one-way modes and their reversible conversion in a double-channel waveguide consisting of two magneto-optical photonic crystals (MOPCs) sandwiched with Al2O3 PC. There exist two pairs of even and odd modes, i.e., M1(even)/M2(odd) or M3(odd)/M4(even) modes, for the double-channel waveguides with one- or two-stranded coupling layer of Al2O3 rods, respectively. Among them, the M1, M2, and M3 modes are caused by the weak coupling strength of two sub-waveguides, while the M4 mode results from the strong coupling effect and supports dispersionless slow-light propagation. Furthermore, we realize the reversible conversion between odd and even modes (i.e., between M1 and M2 modes, or M3 and M4 modes) in the one- or two-stranded structure, respectively, by adjusting the length and position of the perfect electric conductor (PEC) defect properly to cause the desired significant phase delay along the upper and lower equivalent transmission paths. Additionally, we find that the robustness of the M1 even mode is poor because of extra excitations of counter-propagation modes near the right Brillouin boundary, while the other three modes have extremely strong robustness against PEC defects and their one-way transmittances are nearly 100%. These results hold promise for many fields, such as slow-light modulation and the design of topological devices.

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“…Among all these topological systems, the systems relying on the valley Hall effect [53,54] are very promising for experimental realization of topological edge solitons, since they do not require sophisticated longitudinal modulations of the refractive index landscapes leading to additional losses as in Floquet systems [26,27,28,29,30,31,32,33,34,55] or external or artificial magnetic fields as in structured polariton microcavities [41,42,43,44]. In valley Hall systems edge states emerge on the domain wall between two lattice regions due to breaking of the in-version symmetry of the lattice.…”

Section: Introductionmentioning

confidence: 99%

“…In valley Hall systems edge states emerge on the domain wall between two lattice regions due to breaking of the in-version symmetry of the lattice. This symmetry breaking can be achieved, for example, by introducing different detuning into depths of lattice channels at both sides of the domain wall [53,54]. So far, only scalar bright and dark [35,36,37,56] or specific Dirac [57] edge solitons were encountered in valley Hall photonic systems.…”

Section: Introductionmentioning

confidence: 99%

Vector valley Hall edge solitons in superhoneycomb lattices

Tang,

Zhang,

Kartashov

et al. 2022

Preprint

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Topological edge solitons that bifurcate and inherit topological protection from linear edge states and, therefore, demonstrate immunity to disorder and defects upon propagation, attract considerable attention in a rapidly growing field of topological photonics. Valley Hall systems are especially interesting from the point of view of realization of topological edge solitons because they do not require external or artificial magnetic fields or longitudinal modulations of the underlying potential for the emergence of the topological phases. Here we report on the diverse types of vector valley Hall edge solitons forming at the domain walls between superhoneycomb lattices, including bright-dipole, bright-tripole, dark-bright, and dark-dipole solitons. In contrast to conventional scalar topological solitons, such vector states can be constructed as envelope solitons on the edge states from different branches and with different Bloch momenta. Such vector solitons can be remarkably robust, they show stable long-distance propagation and can bypass sharp bends of the domain wall. The existence of the counter-propagating valley Hall edge solitons at the same domain wall allows us to study their structural robustness upon collisions that can be nearly elastic. Our results illustrate richness of soliton families in the valley Hall systems and open new prospects for the light field manipulation and design of the nonlinear topological functional devices.

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Topological Photonic Crystals: Physics, Designs, and Applications

Cited by 190 publications

References 418 publications

On/Off Switching of Valley Topological Edge States in the Terahertz Region

On/Off Switching of Valley Topological Edge States in the Terahertz Region

Reversible Conversion of Odd/Even One-Way Modes in Magneto-Optical Photonic Crystal Double-Channel Waveguides

Vector valley Hall edge solitons in superhoneycomb lattices

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