Spin-entangled orbital angular momentum filter of photons based on a chiral long-period fiber grating.

The orbital angular momentum (OAM) of light is particularly promising for multi-channel data transmission in optical fiber communications. In the implementation, one of the impediments is the lack of an effective all-fiber method to demultiplex and filter OAM modes. To solve the problem, by utilizing the inherent spiral characteristics of a chiral long-period fiber grating (CLPG), we propose and demonstrate experimentally a CLPG-based scheme for filtering spin-entangled OAM of photons. We unveil theoretically and verify experimentally that the co-handed OAM with the same chirality of helical phase wavefront as CLPG couples to higher-order cladding modes and suffers loss, while the cross-handed OAM with the opposite chirality freely passes in CLPG. Meanwhile, by combining its grating characteristics, CLPG can realize the filtering and detection of a spin-entangled OAM with arbitrary order and chirality without exerting extra loss for other OAM. Our work has great potential in analyzing and manipulating spin-entangled OAM, paving the way for the development of all-fiber OAM applications.

A new species of Cinnamomum (Lauraceae) from southwestern China.

Field investigations in Guizhou, China, in 2020 resulted in the discovery of an unknown species of Lauraceae. Morphological studies revealed that it is a new species of CinnamomumSchaeff.sect.Camphora Meisn., based on the large terminal buds, and alternate leaves with pinnate veins. It is distinguished from other species of sect. Camphora by the rather large perulate terminal buds with numerous bracts, larger flowers, oblong-elliptic linear tepals twice as long as the stamens, and the deep cup-shaped fruiting cupule. It is here described and illustrated as a new species, Cinnamomumguizhouense C.Y.Deng, Zhi Yang et Y.Yang. A key to distinguish it from related species in the same area is provided. In addition, we list the new species as Critically Endangered (CR), and suggest to conduct ex situ conservation, collect seeds and plant the species in botanic gardens.

The first complete mitochondrial genome of Matsucoccidae (Hemiptera, Coccoidea) and implications for its phylogenetic position.

The mitochondrial genome (mitogenome) has been extensively used to better understand the phylogenetic relationships within the hemipteran suborder Sternorrhyncha, but sequenced mitogenomes remain unavailable for the entire family Matsucoccidae to date. To address this, here we sequenced the complete mitogenome of Matsucoccusmatsumurae; the first for this family. The mitogenome is 15,360 bp in size and comprises the typical set of 37 mitochondrial genes and a large non-coding region (AT-rich region). Gene order, nucleotide composition and codon usage of protein-coding genes (PCGs) of M.matsumurae differ considerably from those of the other two sequenced Coccidae species. All PCGs were initiated by the ATN start codons and ended with the TAA/G or single T-- stop codons. Nine transfer RNA genes could be folded into typical clover-leaf secondary structures. The length and AT content of the ribosomal RNA genes are highly conserved in the Coccoidea mitogenomes. In contrast, the AT-rich control region is highly variable in size and in the number of tandem repeats. The sliding window analysis showed that the cox1 gene is the most conserved amongst the 13 PCGs, while the ratios of non-synonymous to synonymous substitution rates indicated that the evolution of this mitogenome has been dominated by positive selection. Phylogenetic analyses, based on nucleotide sequence data of 37 mitochondrial genes and amino acid sequence data of 13 PCGs using Bayesian Inference and Maximum Likelihood methods, showed that Matsucoccidae diverged before the Coccidae.