An updated key to the genus Limnophora Robineau-Desvoidy (Diptera: Muscidae) from China, with descriptions of two new species.

A key to the 80 species and 2 subspecies of the genus Limnophora Robineau-Desvoidy, 1830 from China based on males is provided, including two new species Limnophora magnipulvilla sp. nov. and Limnophora apiciflata sp. nov. Photographs of habitus and male genitalia as well as illustrations of the male genitalia of the new species are given.

Ultracompact Polarization Splitter-Rotator Based on Shallowly Etched Subwavelength Gratings and Anisotropic Metasurfaces.

Polarization splitter-rotators (PSRs) are an essential component in on-chip polarization-sensitive and polarization-division multiplexing systems. In this work, we propose an ultracompact and high-performance silicon-based polarization splitter-rotator utilizing anisotropic metasurfaces, which is the first to combine the two, to our knowledge. The tilted periodic metasurface structure has different modulation effects on different polarized light fields, such as the transverse-electric (TE) mode and the transverse-magnetic (TM) mode, which are beneficial for designing polarization management devices. According to the results, the entire length of the silicon PSR was ~13.5 µm. The TE-to-TM conversion loss and polarization conversion ratio ere -0.154 dB and 96.5% at 1.55 µm, respectively. In the meanwhile, the cross talk and reflection loss were -27.0 dB and -37.3 dB, when the fundamental TE mode was input. The insertion loss and cross talk were -0.19 dB and -25.01 dB at the central wavelength when the fundamental TM mode was input. In addition, the bandwidth reached up to ~112 nm with polarization conversion loss and insertion loss higher than -0.46 dB and -0.36 dB. The simulations also show that the designed devices had good fabrication tolerance.

The complete mitochondrial genome of Dicraeus orientalis Becker, 1911 (Diptera: Chloropidae).

Dicraeus orientalis feeds on the seeds of Poaceae. The complete mitochondrial genome of D. orientalis was sequenced and annotated as the first representative of the family Chloropidae. The full length of mitogenome was 16,188 bp, consisting of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNAs). The nucleotide composition was highly A + T biased, accounting for 79.1% of the whole mitogenome. All PCGs start with ATN codons except COI, which end with TAN or incomplete stop codon. ML analysis revealed that Carnoidea was closely related to Ephydroidea and the phylogenetic relationship within Acalyptratae was Tephritoidea + ((Carnoidea + Ephydroidea) + Opomyzoidea).

Large-area all-dielectric metasurface fabricated by an anodized aluminum oxide template.

Transmissive metasurfaces formed by high-index dielectric materials have received great attention due to its potential in holograms, deflectors, beam converters, and flat lenses. However, a key challenge of all-dielectric metasurfaces is the limited scale and high cost in fabrication, such as electron beam lithography (EBL) and focused ion beam (FIB) lithography. In this paper, for the first time to our knowledge, an anodized aluminum oxide (AAO) template is combined with titanium dioxide (TiO2) metasurface fabrication with advantages of large area (>2cm2) and low cost. Using the ordered anodized aluminum oxide (AAO) as an evaporation mask, a TiO2 nanocylinder array is deposited through the AAO mask onto the SiO2 substrate. Electric and magnetic dipole resonances of TiO2 metasurface appear in the visible spectrum. Furthermore, we demonstrate the interaction of the CsPbBr1.5I1.5 quantum dot (QD) emission with magnetic dipole (MD) resonance of TiO2 metasurface. Our results reveal that the metasurface exhibits remarkable photoluminescence (PL) enhancement of 25%. Up to now, a TiO2 metasurface with 2.25-cm2-large area using AAO template method has never been attempted. Different from the metasurfaces fabricated by FIB and EBL, our method offers great ease for large-area metasurface fabrication, which is convenient for metasurface researchers and avoids costly facilities.

Super-Resolution Imaging with Direct Laser Writing-Printed Microstructures.

Dielectric microstructures coupled with a conventional optical microscope have been proven to be a successful way to achieve super-resolution imaging. However, a limitation of such super-resolution imaging is the microstructure fabrication ability, which generally provides natural structures (such as spherical, hemispherical, superhemispherical microlenses, and so on). Meanwhile, the influences of microstructures with complex shapes on the super-resolved imaging still remain unknown. In this paper, direct laser writing (DLW) lithography is used to produce a series of complex microstructures, which are capable of achieving super-resolution imaging in the optical far-field region. Cylinder, truncated cone, hemisphere, and protruding hemisphere microstructures are successfully fabricated by this 3D printing technology, allowing us to resolve features as small as 100 nm under classical microscopy. Moreover, different microstructures lead to different photonic nanojet (PNJ) illuminations and collection efficiencies, resulting in a critical role in super-resolved imaging. The microstructures with spherical surfaces can easily collect the light scattered by the object and convert the high-spatial-frequency evanescent waves into propagating waves.

Switchable Photonic Nanojet by Electro-Switching Nematic Liquid Crystals.

This paper first presents a switchable photonic nanojet (PNJ) generated by a polystyrene (PS) microsphere immersed in nematic liquid crystals (NLCs). The PNJ is switched by applying external voltage, which originates from the refractive index change in the surrounding medium caused by the field-induced realignment of liquid crystal molecules. By tuning the refractive index of NLCs larger or smaller than that of the PS microsphere, the PNJ can be switched off or on. Moreover, we present an optimization study to seek a better electric energy focusing property of the PNJ. Our results reveal that the switchability of PNJ can be optimized by applying a shorter incident wavelength, a double-layer microsphere, and a PS ellipsoid. The full width at half-maximum (FWHM) generated by the PS ellipsoid is narrower than that generated by the microsphere with a shorter incident wavelength. The intensity contrast of the PS ellipsoid is higher than that of the double-layer microsphere. As a whole, the switchability of PNJ can be best optimized by a PS ellipsoid. This should open the way for the development of integrated photonic devices.