Diode-pumped medium-aperture-size square Nd,Y:CaF2 rod amplifier for Inertial Confinement Fusion laser drivers

We demonstrate, for the first time, an 12 mm × 12 mm 0.5%Nd,5% Y:CaF₂ crystal rod having a uniformly-distributed fluorescence spectrum and capable of operating as an amplifying medium at high repetition frequencies. A small gain of 2.7 is experimentally achieved at repetition frequency of 10 Hz for a pump center wavelength of 802 nm, power and absorption efficiency, 61.2 kW and 63.7%, respectively. Spatial-uniformity degradation of the output near-field beam distribution is observed, which should be attributed to the inhomogeneity of Nd,Y:CaF₂ crystal. For a pump power of 61.2 kW, the stored energy of Nd,Y:CaF₂ amplifier is 3.73 J. When the input energy is 50 mJ, the output laser energy is 1.4 J of extraction efficiency up to 37.53% after four-pass amplification.     

Mode disorder in elliptical hole PCFs

In the elliptical-hole photonic crystal fibers, when the central defect air hole is large enough, the modes will be disordered. The order of the HE₁₁-like mode is investigated in detail based on the full vector supercell overlapping method. The degeneracy will be enhanced at the frequency where the modes begin to be disordered.     

Study on electronic blocking layer of 403 nm GaN-based vertical cavity surface emitting lasers

In order to obtain good optical characteristics in the GaN-based vertical-cavity surface-emitting laser (VCSEL), different kinds of AlGaN electron blocking layers (EBL) were introduced. These were inserted coherently near the active region to limit electron leakage into the p-doped side. The research was conducted by photonic integrated circuit simulator in three-dimensional (PICS3D). The simulated results reveal that an EBL can improve the optical characteristics of a VCSEL effectively. All the advantages are due to a reduction in the electron leakage in the quantum wells. While the voltage of the five-layer EBLs LD is lower than the voltage of the seven-layer EBLs LD, the output power of the two is approximately the same, so the five-layer EBLs is the best choice for comprehensive structure analysis as the epitaxial structure can be grown more easily on it.     

A comprehensive review on poly(3-alkylthiophene)-based crystalline structures,protocols and electronic applications

Poly (3-alkylthiophenes) (P3ATs) particularly poly (3-hexylthiophene) (P3HT) have vigorous tendency to crystallize into the ordered morphologies, thereby reflect the efficient electrical and optical characteristics. Here, the remarkable crystalline structures of P3ATs comprising single crystals, nanofibers, nano/microwires, nanoribbons, micelles, nanowhiskers, thin films, spherulites, etc. are thoroughly reviewed. In each category, the principle aspects like preparation methodologies (e.g., self-seeding, shearing, electrospinning, self-organization, epitaxial solidification, etc.), micro/nanostructures, orientation and optical properties are meticulously brought into consideration. Applications of the ordered P3AT structures in solar cells, organic field-effect transistors, and sensors as well as the theoretical studies are also highlighted. Furthermore, the polymorphism, sol-gel, nanoparticles, liquid crystalline morphology, and two-dimensional sheets are reviewed.     

TiO2/SnOxCly double layer for highly efficient planar perovskite solar cells

Recently, perovskite solar cells have attracted tremendous research interest due to their amazing light to electric power conversion efficiency (PCE). However, most high performance devices usually use mesoporous TiO₂ as the electron transport layer (ETL), which increases cost for practical application. Here, TiO₂/SnO_xCl_y double layer was employed as the ETL for planar perovskite solar cells. Compared with bare TiO₂, perovskite solar cell based on TiO₂/SnO_xCl_y shows drastically improved power conversion efficiency and reduced hysteresis. These improvements are attributed to TiO₂/SnO_xCl_y which could enhance electron extraction and reduce surface trap-state.     

UHV sample holder for fast heating and cooling cycles

We describe a UHV sample holder that allows fast heating and cooling cycles between 77 K and 1300 K. The system allows us to perform thermal treatment of a sample. The samples are heated by electron bombardment and the cooldown is achieved by liquid nitrogen (LN₂). The sample holder is designed to be assembled in a multitechnique surface analysis apparatus that performs AES, SIMS, TDS and XPS analysis.     

Fiber optic and light scattering sensors: Complimentary approaches to rapid detection of Salmonella enterica in food samples

Salmonella-related foodborne infections present a major public health problem worldwide despite more stringent regulations. Salmonella enterica serovars Enteritidis and Typhimurium are the two most frequent causes of poultry related outbreaks; therefore, their rapid and accurate detection would improve Salmonella control at the farm, processing plant, and at retail. In this study, we investigated if a fiber optic immunosensor and light scattering sensor, BARDOT (bacterial rapid detection using optical scattering technology) could facilitate the detection of these two serovars in naturally contaminated poultry (n = 50). The fiber optic sensor with a detection limit of 10³ CFU/ml identified S. enterica in selective enrichment broth in less than 12 h. The colonies (1.0 ± 0.2 mm) produced by plating the enriched samples on selective XLT4 agar for 13–15 h were scanned using BARDOT and S. enterica was identified after matching individual colony scatter patterns to the scatter image library with a sample-to-answer time of about 24 h. Both sensors identified 4 positive samples (8%), which corresponded to the results of the USDA-FSIS protocol, PCR, and lateral flow immunoassays. The colony scatter patterns identified all natural isolates as S. Enteritidis, which was further verified by serovar-specific PCR. The sensors used individually or in combination demonstrate potential for accurate and rapid detection of S. enterica in poultry.