Controlling light absorption of graphene at critical coupling through magnetic dipole quasi-bound states in the continuum resonance

Wang, Xing; Duan, Junyi; Chen, Wenya; Zhou, Chaobiao; Liu, Tingting; Xiao, Shuyuan

doi:10.1103/physrevb.102.155432

Cited by 179 publications

(71 citation statements)

References 51 publications

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“…Fano resonant metasurfaces have been widely studied in nanophotonics. More recently, there has been significant work devoted to realize high-quality factor Fano resonances for optical and visible frequencies based on bound states in the continuum (BICs) [35][36][37][38][39][40][41]. Due to their enhanced light-matter interactions, these BIC metasurfaces can be efficiently employed in nonlinear optics applications [35].…”

Section: Principle Of Operation Of Nonlinearity-based Nonreciprocal Devices Based On Coupled Fano Metasurfacesmentioning

confidence: 99%

Free-Space Nonreciprocal Transmission Based on Nonlinear Coupled Fano Metasurfaces

2021

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Optical nonlinearities can enable unusual light–matter interactions, with functionalities that would be otherwise inaccessible relying only on linear phenomena. Recently, several studies have harnessed the role of optical nonlinearities to implement nonreciprocal optical devices that do not require an external bias breaking time-reversal symmetry. In this work, we explore the design of a metasurface embedding Kerr nonlinearities to break reciprocity for free-space propagation, requiring limited power levels. After deriving the general design principles, we demonstrate an all-dielectric flat metasurface made of coupled nonlinear Fano silicon resonant layers realizing large asymmetry in optical transmission at telecommunication frequencies. We show that the metrics of our design can go beyond the fundamental limitations on nonreciprocity for nonlinear optical devices based on a single resonance, as dictated by time-reversal symmetry considerations. Our work may shed light on the design of flat subwavelength free-space nonreciprocal metasurface switches for pulsed operation which are easy to fabricate, fully passive, and require low operation power. Our simulated devices demonstrate a transmission ratio >50 dB for oppositely propagating waves, an operational bandwidth exceeding 600 GHz, and an insertion loss of <0.04 dB.

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Section: Principle Of Operation Of Nonlinearity-based Nonreciprocal Devices Based On Coupled Fano Metasurfacesmentioning

confidence: 99%

Free-Space Nonreciprocal Transmission Based on Nonlinear Coupled Fano Metasurfaces

2021

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“…Zhang et al [ 37 ] showed that optical absorption in graphene can be enhanced based on BIC using a sphere–graphene–slab structure, and ultrasensitive absorption of graphene can be obtained via the excitation of GSPPs. Later, Wang et al [ 38 ] showed that light absorption in graphene can be controlled by asymmetric parameter of suspended silicon nanodisk, and maximum absorption of 50% can be realized at critical coupling through quasi-BIC in the two-port system composed of graphene. However, achieving highly efficient light absorption of monolayer graphene within a comparatively simple architecture is still rare, and a theoretical model based on critical coupling for perfect or near-perfect light absorption of graphene in the two-port system needs to be developed.…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient Light Absorption of Monolayer Graphene by Quasi-Bound State in the Continuum

et al. 2021

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Graphene is an ideal ultrathin material for various optoelectronic devices, but poor light–graphene interaction limits its further applications particularly in the visible (Vis) to near-infrared (NIR) region. Despite tremendous efforts to improve light absorption in graphene, achieving highly efficient light absorption of monolayer graphene within a comparatively simple architecture is still urgently needed. Here, we demonstrate the interesting attribute of bound state in the continuum (BIC) for highly efficient light absorption of graphene by using a simple Si-based photonic crystal slab (PCS) with a slit. Near-perfect absorption of monolayer graphene can be realized due to high confinement of light and near-field enhancement in the Si-based PCS, where BIC turns into quasi-BIC due to the symmetry-breaking of the structure. Theoretical analysis based on the coupled mode theory (CMT) is proposed to evaluate the absorption performances of monolayer graphene integrated with the symmetry-broken PCS, which indicates that high absorption of graphene is feasible at critical coupling based on the destructive interference of transmission light. Moreover, the absorption spectra of the monolayer graphene are stable to the variations of the structural parameters, and the angular tolerances of classical incidence can be effectively improved via full conical incidence. By using the full conical incidence, the angular bandwidths for the peak absorptivity and for the central wavelength of graphene absorption can be enhanced more than five times and 2.92 times, respectively. When the Si-based PCS with graphene is used in refractive index sensors, excellent sensing performances with sensitivity of 604 nm/RIU and figure of merit (FoM) of 151 can be achieved.

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“…In the far-infrared and terahertz band, a striking feature of graphene unlike traditional precious metals is that its surface plasmon resonance (SPR) has an extremely strong field confinement and lower ohmic loss. It can be closely combined with deep subwavelength nano-level light [39][40][41][42][43][44][45], which greatly promotes its light absorption rate in many devices, such as photoelectric sensors, optical detectors, waveguides, and ultra-fast switches [46][47][48][49][50]. In addition, the most significant feature of graphene plasmons is that the surface conductivity of graphene can be adjusted by changing the Fermi level or chemical potential.…”

Section: Introductionmentioning

confidence: 99%

A Tunable “Ancient Coin”-Type Perfect Absorber with High Refractive Index Sensitivity and Good Angular Polarization Tolerance

Luo

Shangguan

et al. 2021

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In this paper, we design and present a graphene-based “ancient coin”-type dual-band perfect metamaterial absorber, which is composed of a silver layer, silicon dioxide layer, and a top “ancient coin” graphene layer. The absorption performance of the absorber is affected by the hollowed-out square in the center of the graphene layer and geometric parameters of the remaining nano disk. The optical properties of graphene can be changed by adjusting the voltage, to control the absorption performance of the absorber dynamically. In addition, the centrally symmetric pattern structure greatly eliminates the polarization angle dependence of our proposed absorber, and it exhibits good angular polarization tolerance. Furthermore, the proposed “ancient coin”-type absorber shows great application potential as a sensor or detector in biopharmaceutical, optical imaging, and other fields due to its strong tunability and high refractive index sensitivity.

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Controlling light absorption of graphene at critical coupling through magnetic dipole quasi-bound states in the continuum resonance

Cited by 179 publications

References 51 publications

Free-Space Nonreciprocal Transmission Based on Nonlinear Coupled Fano Metasurfaces

Free-Space Nonreciprocal Transmission Based on Nonlinear Coupled Fano Metasurfaces

Highly Efficient Light Absorption of Monolayer Graphene by Quasi-Bound State in the Continuum

A Tunable “Ancient Coin”-Type Perfect Absorber with High Refractive Index Sensitivity and Good Angular Polarization Tolerance

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