Search

In this study, a novel hybrid surface plasmon waveguide structure based on CdS nanowires and metal ridges was designed. The waveguide structure was simulated and analysed at a working wavelength of 490 nm based on the finite element method. The electric field distribution, mode characteristics, transmission length and quality factor of the waveguide were studied with geometric parameters. Results show that the comprehensive performance of the waveguide can be significantly optimised by appropriately adjusting the geometric parameters of the structure. Through the optimal parameter design, the effective mode field area reaches 0.008 λ 2 , the transmission length is 21,289 nm, and the quality factor is 702.12. This waveguide structure has great potential in the fields of optoelectronic communication and optical sensing technology.

It has been proposed that anoxic and iron-rich (ferruginous) marine conditions were common through most of Earth history. This view represents a major shift in our understanding of the evolution of marine chemistry. However, thus far, evidence for ferruginous conditions comes predominantly from Fe-speciation data. Given debate over these records, new evidence for Fe-rich marine conditions is a requisite if we are to shift our view regarding evolution of the marine redox landscape. Here we present strong evidence for ferruginous conditions by describing a suite of Fe-rich chemical sedimentary rocks—banded iron formation (BIF)—-deposited during the Early Cambrian in western China. Specifically, we provide new U-Pb geochronological data that confirm a depositional age of ca. 527 Ma for this unit, as well as rare earth element (REE) data are consistent with anoxic deposition. Similar to many Algoma-type Precambrian iron formations, these Early Cambrian sediments precipitated in a back-arc rift basin setting, where hydrothermally sourced iron drove the deposition of a BIF-like protolith, the youngest ever reported of regional extent without direct links to volcanogenic massive sulphide (VMS) deposits. Their presence indicates that marine environments were still characterized by chemical- and redox-stratification, thus supporting the view that—despite a dearth of modern marine analogues—ferruginous conditions continued to locally be a feature of early Phanerozoic seawater.