分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: We study an anisotropic two-dimensional non-Hermitian Lieb lattice, where the staggered gain and loss present in the horizontal and vertical directions, respectively. The intra-cell nonreciprocal coupling generates magnetic flux enclosed in the unit cell of the Lieb lattice and creates nontrivial topology. The active and dissipative topological edge states are along the horizontal and vertical directions, respectively. The two-dimensional non-Hermitian Lieb lattice also supports passive topological corner state. At appropriate magnetic flux, the non-Hermiticity can alter the corner state from one corner to the opposite corner as the non-Hermiticity increases. The gapless phase of the Lieb lattice is characterized by different configurations of exceptional points in the Brillouin zone. The topology of the anisotropic non-Hermitian Lieb lattices can be verified in many experimental platforms including the optical waveguide lattices, photonic crystals, and electronic circuits.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Maxwell fisheye lens was proposed to pinpoint super-resolution with the addition of wave drain and the interaction of multiple drains is theoretically predicted to improve subwavelength resolution further. In this paper we discuss the role played by port drains in optical absolute instruments, and verify by full-wave simulation that coupling nature for wave source and drain applies correctly in the picture of scanning imaging for absolute instrument. This work prospects for scanning near fields shaped from far-field wave propagation.