Coexistence of a new type of bound state in the continuum and a lasing threshold mode induced by PT symmetry

Song, Qianju; Hu, Jiashun; Dai, Shiwei; Zheng, Chunxiong; Han, Dezhuan; Zi, Jian; Zhang, Zhao-Qing; Chan, Che Ting

doi:10.1126/sciadv.abc1160

Cited by 63 publications

(35 citation statements)

References 45 publications

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“…The wavelength-dependent complex refractive index of Si is extracted from experimental data 49 , and the constant refractive index of 1.45 is assigned to SiO 2 . Note that we choose the dimer design as it belongs to a symmetric geometry of C 2v group and possesses more structural parameters to be tuned than C 4v configurations [50][51][52][53][54][55][56][57][58][59] . Benefiting from the additional degree of freedom, it is possible to manipulate the excitation of dual BIC resonances by adjusting the structural geometry and rotating the fundamental pump polarization.…”

Section: Polarization-controlled Dual Bound States In the Continuummentioning

confidence: 99%

Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum

Xiao,

Qin,

Duan

et al. 2022

Preprint

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Tailoring optical nonlinear effects (e.g. harmonic generation, sum-frequency mixing, etc.) in the recently emerging all-dielectric platform is important for both the fundamental science and industrial development of high-efficiency, ultrafast, and miniaturized photonic devices. In this work, we propose a novel paradigm for dynamically switchable high-harmonic generation in Silicon nanodimer metasurfaces by exploiting polarization-controlled dual bound states in the continuum (BIC). Owing to the high-quality factor of BIC resonances, efficient harmonic signals including the third-harmonic generation and fifth-harmonic generation from a direct process as well as a cascaded process by degenerate four-wave mixing are obtained. Moreover, the BICs and their resonantly enhanced harmonics can be switched on or off with high selectivity respect to the fundamental pump polarization. Compared with previous reports, our work provide a simple but effective tuning strategy by fully exploring the structural symmetry and polarization degree of freedom rather than resorting to additional external stimuli, which would have great advantages in smart designing tunable and switchable nonlinear light source for chip-scale applications.

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Section: Polarization-controlled Dual Bound States In the Continuummentioning

confidence: 99%

Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum

Xiao,

Qin,

Duan

et al. 2022

Preprint

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“…A PT -symmetric Hamiltonian satisfies [ Ĥ, P T ] = 0, with the joint parity-time operator ( P T ). PT -symmetric non-Hermitian Hamiltonians feature unconventional properties in numerous systems ranging from classical [4][5][6][7][8][9][10][11][12][13][14][15] to quantum systems [16][17][18][19][20][21][22][23][24][25][26]. When the Hamiltonian parameters cross the exceptional point (EP), PT symmetry is broken, leading to a symmetry-breaking transition.…”

Section: Introductionmentioning

confidence: 99%

Experimental demonstration of coherence flow in $\mathcal{PT}$- and anti-$\mathcal{PT}$-symmetric systems

Fang,

Zhao,

Zhang

et al. 2021

Preprint

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Non-Hermitian parity-time (PT ) and anti-parity-time (APT )-symmetric systems exhibit novel quantum properties and have attracted increasing interest. Although many counterintuitive phenomena in PT -and APT -symmetric systems were previously studied, coherence flow has been rarely investigated. Here, we experimentally demonstrate single-qubit coherence flow in PT -and APT -symmetric systems using an optical setup. In the symmetry unbroken regime, we observe different periodic oscillations of coherence. Particularly, we observe two complete coherence backflows in one period in the PT -symmetric system, while only one backflow in the APT -symmetric system. Moreover, in the symmetry broken regime, we observe the phenomenon of stable value of coherence flow. We derive the analytic proofs of these phenomena and show that most experimental data agree with theoretical results within one standard deviation. This work opens avenues for future study on the dynamics of coherence in PT -and APT -symmetric systems.

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“…In the last two decades, BICs have been observed in many photonic structures such as photonic crystals, metasurfaces, [2][3][4], chains of coupled resonators [5][6][7][8], waveguides [9][10][11][12][13] and even single subwavelength resonators supporting quasi-BIC in a form of supercavity modes [14][15][16]. A divergent radiative quality (Q) factor, strong spatial localization, and drastic enhancement of the incident field make BICs very prospective for many applications including lasers [17][18][19][20][21][22][23][24][25], optical filters [26][27][28], biological and chemical sensors [29][30][31][32][33], and non-linear photonics [34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Bound states in the continuum in periodic structures with structural disorder

Maslova¹,

Rybin²,

Bogdanov³

et al. 2021

Preprint

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We study the effect of structural disorder on the transition from the bound states in the continuum (BICs) to quasi-BICs by the example of the periodic photonic structure composed of two layers of parallel dielectric rods. We uncover the specificity in the robustness of the symmetry-protected and accidental BICs against various types of structural disorder. We analyze how the spatial mode localization induced by the structural disorder results in an effective reduction of the system length and limits the Q factor of quasi-BICs. Our results are essential for the practical implementation of BICs especially in natural and self-assembled photonic structures, where the structural disorder plays a crucial role.

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Coexistence of a new type of bound state in the continuum and a lasing threshold mode induced by PT symmetry

Cited by 63 publications

References 45 publications

Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum

Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum

Experimental demonstration of coherence flow in $\mathcal{PT}$- and anti-$\mathcal{PT}$-symmetric systems

Bound states in the continuum in periodic structures with structural disorder

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