分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this paper, we theoretically study the Floquet engineering of two dimensional photonic waveguide arrays in three types of lattices: honeycomb lattice with Kekule distortion, breathing square lattice and breathing Kagome lattice. The Kekule distortion factor or the breathing factor in the corresponding lattice is periodically changed along the axial direction of the photonic waveguide with frequency $\omega$. Within certain ranges of $\omega$, the Floquet corner states in the Floquet band gap of quasi-energy spectrum are found, which are localized at the corner of the finite two-dimensional arrays. Due to particle-hole symmetric in the model of honeycomb and square lattice, the quasi-energy level of the Floquet $\pi$ corner states is $\pm\omega/2$. On the other hand, Kagome lattice does not have particle-hole symmetric, so that the quasi-energy level of the Floquet $\pm2\pi/3$ corner states is near to $\pm1\omega/3$. The corner states are either protected by crystalline symmetry or reflection symmetry. The finding of Floquet fractional-$\pi$ corner states could provide more options for engineering of on-chip photonic devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this study, we theoretically and numerically investigate the resonant modes and reflectance of an optical grating consisting of a wavy dielectric slab by applying the spectral element method. The presence of the wavy shape transforms the waveguide modes into leaky resonant modes. A few resonant modes with specific longitudinal wave number have infinitely large Q factor, while the other resonant modes have finite Q factor. For the leaky resonant mode with zero longitudinal wave number, the Q factor is inversely proportional to the amplitude of the wavy shape. An array of multiple low-Q wavy gratings has a high reflectance in a large bandwidth. A double-layer wavy grating forms a Fabry-Perot cavity, which hosts Fabry-Perot bound states in the continuum (BICs) at the resonant frequency. The Q-factor of the Fabry-Perot cavity can be tuned by adjusting the distance between the two wavy slabs. The wavy shape could be generated by a vibrational wave in a flat dielectric slab so that the BICs mode and wideband reflectance could be controlled on-demand.
点击量
待评议
点击量
下载量
评论
