论文标题
光向指导中连续体中归化状态的起源：由于模式交叉而引起的平均对称性破裂
Origin of degenerate bound states in the continuum in a grating waveguide: Parity symmetry breaking due to mode crossing
论文作者
论文摘要
我们通过无限颗粒本征模的分析理论解释了平面光栅波导中连续态（BIC）中结合状态的起源。常规对称性保护的BIC是在正常发生率下形成的，主要是由单个无限粒的本征模在BIC共振两侧具有奇怪的空间奇偶校验。奇怪的奇偶校验是从放射线损失通道和这种BIC出现的出现的原因。退化BIC出现在两个无限粒本征元的退化频率附近的机理是不同的。退化的BIC是由两个交叉无限粒的特征模的反式相干叠加形成的，两者都具有混合的奇偶校验和经历平等对称性破坏，因为频率通过退化点进行扫描。在这种情况下，由于两个交叉特征模的破坏性干扰，从放射线损耗通道和极高的Q狭窄共振获得了截止。这种机制的实施可以具有指导性，可以在其他光子晶体和结构中设计BIC。
We explain the origin of bound states in the continuum (BICs) in a planar grating waveguide, in particular, a mechanism for formation of degenerate BICs, via the analytical theory of the infinite-grating eigenmodes. Conventional symmetry-protected BICs are formed at normal incidence mainly by a single infinite-grating eigenmode that has an odd spatial parity on both sides of the BIC resonance. The odd parity is the reason for a cutoff from the radiation-loss channel and appearance of such BICs. The mechanism of emergence of a degenerate BIC in a vicinity of a degenerate frequency of two infinite-grating eigenmodes is different. The degenerate BIC is formed by an anti-phased coherent superposition of two crossing infinite-grating eigenmodes both of which possess a mixed parity and experience parity symmetry breaking as the frequency scans through the degeneracy point. In this case a cutoff from the radiation-loss channel and extremely high-Q narrow resonance is achieved due to the destructive interference of the two crossing eigenmodes. Implementation of such a mechanism can be instructive for designing BICs in other photonic crystals and structures.
