ABSTRACT
Electromagnetic wave transmission in a magneto-optical (MO) medium is a basic and old topic but has raised new interest in recent years, because MO medium plays a vital role in optical isolator, topological optics, electromagnetic field regulation, microwave engineering, and many other technological applications. Here, we describe several fascinating physical images and classical physical variables in MO medium by using a simple and rigorous electromagnetic field solution approach. We can easily obtain explicit formulations for all relevant physical quantities, such as the electromagnetic field distribution, energy flux, reflection/transmission phase, reflection/transmission coefficients, and Goos-Hänchen (GH) shift in MO medium. This theory can help to deepen and broaden our physical understanding of basic electromagnetics, optics, and electrodynamics in application to gyromagnetic and MO homogeneous medium and microstructures, and might help to disclose and develop new ways and routes to high technologies in optics and microwave.
ABSTRACT
The magneto-optical (MO) materials are essential for designing nonreciprocal devices, like isolators and circulators. Even though the study of MO effect has a long history, the recent works of fabricating nonreciprocal nanostructures, novel MO metamaterials, and topological photonics have garnered significant attention in both theoretical and experimental research of MO materials. In this work, we consider the planar MO waveguide mode. By setting the general form of the fields and utilizing the boundary conditions, the analytical solution of MO modes is obtained. We have shown the potential of such effective solution in analyzing the dispersions and transport behaviors of MO modes in the waveguide. Crossings and avoided crossings of modes will happen, which may due to the strong coupling of TE and TM modes in the waveguide. Faraday rotation can be observed during the propagation of MO modes and the energy flow will precess in the waveguide. These results can be applied in predicting the evolution of the modes in MO waveguides, which has potential in designing MO nonreciprocal devices.
ABSTRACT
Out-of-plane lattice plasmons (OLPs) show great potential in realizing high-quality factors due to the strong interparticle coupling. However, the strict conditions of oblique incidence bring challenges to experimental observation. This Letter proposes a new, to the best of our knowledge, mechanism to generate OLPs: through near-field coupling. Notably, with specially designed nanostructure dislocation, the strongest OLP can be achieved at normal incidence. The direction of energy flux of the OLPs is mainly determined by the wave vectors of Rayleigh anomalies. We further found that the OLP exhibits symmetry-protected bound states in the continuum characteristic, which explains the failure of previously reported symmetric structures to excite OLPs at normal incidence. Our work extends the understanding of the OLP and brings benefit to promote the flexible design of functional plasmonic devices.
ABSTRACT
Stably Expressed Genes (SEGs) are a set of genes with invariant expression. Identification of SEGs, especially among both healthy and diseased tissues, is of clinical relevance to enable more accurate data integration, gene expression comparison and biomarker detection. However, it remains unclear how many global SEGs there are, whether there are development-, tissue- or cell-specific SEGs, and whether diseases can influence their expression. In this research, we systematically investigate human SEGs at single-cell level and observe their development-, tissue- and cell-specificity, and expression stability under various diseased states. A hierarchical strategy is proposed to identify a list of 408 spatial-temporal SEGs. Development-specific SEGs are also identified, with adult tissue-specific SEGs enriched with the function of immune processes and fetal tissue-specific SEGs enriched in RNA splicing activities. Cells of the same type within different tissues tend to show similar SEG composition profiles. Diseases or stresses do not show influence on the expression stableness of SEGs in various tissues. In addition to serving as markers and internal references for data normalization and integration, we examine another possible application of SEGs, i.e., being applied for cell decomposition. The deconvolution model could accurately predict the fractions of major immune cells in multiple independent testing datasets of peripheral blood samples. The study provides a reliable list of human SEGs at the single-cell level, facilitates the understanding on the property of SEGs, and extends their possible applications.
ABSTRACT
Tamm plasmons (TPs), whose plasmon modes are confined at the Bragg reflector/metal interface due to the photonic stopband of the reflector and the negative dielectric constant of the metal, exhibit many advantages over the conventional surface plasmons (SPs) and potential applications in sensors, filters, optical circuits and light-emitting devices. In this paper, a TP-cavity structure has been proposed for accelerating the light emission and alleviating the large metal loss, which is hopeful for solving the efficiency droop and "green gap" problems in InGaN green light-emitting diodes (LEDs). The light emission performance of TP-cavity LEDs was systematically investigated based on transfer matrix and finite-difference time domain methods. Purcell factor (Fp) and light extraction efficiency (LEE) were both remarkably enhanced, which would be attributed to the presence of the TP and/or SP modes induced by the TP-cavity structure. In addition, two important factors including the thicknesses of the top Ag film and medium layer were investigated in detail and taken into account for the balance between the Fp and the LEE. Finally, light emission intensity was significantly enhanced for the TP-cavity green LEDs after the structure optimization as compared to the conventional green LEDs.