High-order nonreciprocal add-drop filter

Li, Hang; Ge, Rui; Peng, Yuchen; Yan, Bei; Xie, Jianlan; Liu, Jing; Wen, Shuangchun

doi:10.1007/s11433-021-1776-8

Cited by 9 publications

(3 citation statements)

References 74 publications

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“…The above properties of the multiband-like edge and corner states are of great importance for practical applications such as photonic wavelength demultiplexers. [56,57] The advantage of the above multiple photonic topological system is that the edge and corner states are demultiplexed both spectrally and spatially, unlike the preceding ones with only spectral demultiplexing performances (see e.g., [57] ). The above spectral and spatial divisions of topological edge and corner states pave the way toward the practical applications, including multichannel wavelength demultiplexer with significantly low background noises, highly sensitive biosensing, and optical switching with large modulation depth.…”

Section: Resultsmentioning

confidence: 99%

“…We also show that filling anomaly originated from the disagreement of the number of occupied bands below the common gap occurs in the photonic structure composed of two different nontrivial subsystems, resulting in second-order corner states with fractional corner charge of 1/4, which is confirmed again by calculating spectral charge distributions. Spatially as well as spectrally separated multiband-like corner states exist in such a multiple topological photonic system, which can be used for many applications such as wavelength demultiplexing [56,57] and optical sensing.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Second‐Order Topological Photonic Systems for Multichannel Beam Splitting and Wavelength Demultiplexing

Kim

2022

Physica Rapid Research Ltrs

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Although second‐order topological photonic systems have been extensively investigated in the last several years, topological edge and corner states have been considered mainly in the systems with single topology. Herein, multiple topological photonic systems consisting of two different types of topologically nontrivial unit cells and their trivial counterparts which are related to each other under a relevant continuous transformation are presented. The dispersing characteristics of edge states are diverse at different topological interfaces of the system and can be controlled with relevant structural parameters, resulting in novel mechanism for multichannel topological beam splitting. Interestingly enough, second‐order topological corner states exist even in the structure of nontrivial photonic crystals surrounded by another nontrivial one unlike the previous cases with trivial surroundings, which can be confirmed from the spectral charge distributions. This enables us to obtain both spatially and spectrally separated multiband‐like corner states as well as edge ones in a multiple topological photonic system, which can be used for wavelength demultiplexer. The results in this work will trigger extensive studies on multiple topology for wide photonic applications.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiple Second‐Order Topological Photonic Systems for Multichannel Beam Splitting and Wavelength Demultiplexing

Kim

2022

Physica Rapid Research Ltrs

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“…Compared with the PC line-defect waveguide [3], the PC Coupled-Resonator-Optical Waveguide [4,5] can primarily achieve the group velocity dispersion (GVD)-free at the central frequencies without dispersion compensation techniques [6,7]. However, the size and Q of resonators are essential to obtain characteristics of low group velocity v g and low loss [8][9][10][11]. For achieving high-Q PC cavities, * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Slow light in topological coupled-corner-state waveguide

Liu¹,

Wang²,

Li³

et al. 2022

J. Phys. D: Appl. Phys.

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We theoretically propose a Coupled-Corner-State Waveguide (CCSW), which is composed of a zigzag edge-like structure based on C-4 symmetrical lattice. CCSW mode is achieved by weak coupling between a sequence of higher order topological corner state (TCS). Based on the tight-binding (TB) approximation, the flat dispersion relation of CCSW mode is obtained, and suitable for slowing down light. The characteristics of slow light, including the group index and group velocity dispersion, are discussed in detail. At the eigenfrequency of individual TCS, the group velocity dispersion of CCSW mode is zero. Importantly, the CCSW mode shows strong robustness when introducing disorders, compared with the conventional Coupled-Resonator-Optical Waveguide (CCROW) based on photonic crystal defect cavities. Our findings may find topological slow light applications such as optical buffers, the processing of optical signals, optical delay lines and so on.

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