Based on the transfer-matrix method, we theoretically explore the transmission and reflection properties of light waves in a one-dimensional defective photonic crystal composed of superconductor (HgBa₂Ca₂Cu₃O_8+δ) and semiconductor (GaAs) layers. The whole system is centrosymmetric and can generate a defect transmission peak in the photonic band gap. We study the effect of the temperature on the defect mode. Results obtained show that the defect mode shifts to the lower frequency regions as the value of the environmental temperature increases, and the resonance of the defect mode can be strengthened further as the number of periods increases. In addition, our findings reveal that the central wavelength of the defect mode increases with the increase in the environmental temperature and it presents a nearly linear relationship between the central wavelength of the defect mode and the temperature in cryogenic environments. Therefore, we can use the temperature response of the defect mode to detect the temperature. It is hoped that this study has potential applications for the development of cryogenic sensors with high sensitivity.

Topological waveguide arrays, which support robust light propagation through edge modes, offer a promising solution for fault-tolerant photonic chips. However, these arrays commonly require a considerable number of waveguide elements to ensure their topological protection, leading to increased footprint and fabrication costs. Here, we propose a topological waveguide array with only a few cells based on a photonic Aharonov-Bohm (AB) cage. This design is advantageous because the edge modes become compactly localized at the boundary waveguides. We achieve this by utilizing the orbital hybridization of the fundamental mode and first-order orbital angular momentum (OAM) modes to construct the AB cage, where arbitrary flux of artificial gauge fields (AGFs) can be generated and controlled by adjusting the angle between adjacent waveguides. Notably, these edge modes exhibit robustness against disorders of on-site potential and coupling, even within a small lattice. Furthermore, we demonstrate the extension of this mechanism to high-order OAM modes. Our work paves the way for miniaturizing topological devices using the orbital degree of freedom, holding the potential for exploring other AGF-enriched phenomena.

We theoretically analyze the enhancement and regulation of Goos-Hänchen (GH) shift in hyperbolic metamaterials in the near-infrared band. For a given incident wavelength, photonic crystals composed of graphene and dielectric present hyperbolic dispersion characteristics by modulating the Fermi energy of graphene. The phase of the reflection coefficient changes dramatically near the phase transition from hyperbolic dispersion to elliptic dispersion, and subsequently giant GH shift is achieved at the resonant angle. The largest GH shift is as high as 300λ. Great GH shift can be effectively realized by regulating the layers of graphene and the thickness of the dielectric as well. It is hoped that this research may provide theoretical guidance for the design of high-sensitivity sensors based on the GH shift effect in hyperbolic metamaterials.

We explore theoretically Goos-Hänchen (GH) shift around the defect mode in superconducting defective photonic crystals (PCs) in cryogenic environment. The defective PCs are constructed by alternating semiconductors and superconductors. A defect mode arises in the photonic bandgap and sensitively depends on environment temperature and hydrostatic pressure. Reflection and transmission coefficient phases make an abruptly jump at the defect mode and giant GH shifts have been achieved around this mode. The maximum GH shift can get as high as 10³λ (incident wavelength), which could be modulated by the values of temperature and hydrostatic pressure. This study may be utilized for pressure- or temperature-sensors in cryogenic environment.

We theoretically investigate the defect mode transmittance of light waves in superconductor–semiconductor photonic crystals and its pressure-sensing dependence. The photonic crystal is composed of alternating superconducting and semiconducting slabs and a defect locates at the center of this structure. Two trapezoid waveguides are fixed at both sides of the crystal, which induces the hydrostatic pressure applied and beams transmitted simultaneously. The resonant wavelength variation in the defect mode is directly proportional to the pressure applied on the system in the near-IR region, which can be utilized for linear pressure sensors in the cryogenic environment. Pressure sensitivity reaches a high value of 2.6 nm/GPa, which is higher than that in the study based on the reflection spectra. The sensitivity coefficient may be modulated by the environment temperature as well. This study has potential regarding pressure-light-wave sensors.