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Insect herbivores and arbuscular mycorrhizal fungi (AMF) often occur simultaneously on a host plant, altering plant morphological and biochemical traits and thereby not only affecting each other’s performance, but also plant interactions with subsequent above- or belowground herbivores. Here, we investigate the combined effects of AMF and above- and belowground herbivory on plant productivity and performance of subsequent above- and belowground herbivores. We conducted a 3×2 full-factorial experiment with three factors of ‘Herbivory (no herbivory, leaf herbivory, and tuber herbivory) and two factors of ‘AMF inoculation’ (no AMF inoculation and AMF inoculation) in the tuber-plant, potato (Solanum tuberosum). We showed that both AMF and tuber herbivory increased tuber biomass and tuber primary metabolites (protein, starch). Tuber herbivory reduced the performance of subsequent conspecifics feeding on leaves potentially via increased leaf levels of phenolics, α-solanine and α-chaconine. By contrast, it increased the performance of subsequent conspecifics feeding on tubers potentially via increased protein, however, only in plants inoculated with AMF. This indicates that the belowground facilitation among conspecific insects was contingent upon the presence of AMF. Leaf herbivory did not affect subsequent above- or belowground insect performance. These feedings improve our understanding of the ecological consequences of antagonists and mutualists interactions mediated by phytochemistry, especially for agroecosystems.

Herbivores use plant chemicals for host plant selection to maximize their own and/or offspring performance. Since host plants that are optimal for mother and offspring are often different and spatially/temporally separated, it remains unclear how plant chemicals are associated with trade-offs between adult preference and larval performance. We found that adults of the rice water weevil (Lissorhoptrus oryzophilus), one of the most important pests on rice in the world, preferred volatiles from barnyard grass over rice and tended to feed and oviposit on barnyard grass compared with rice. In contrast, larvae performed better on rice roots than on barnyard grass roots. Chemical analyses further showed that rice roots had higher nitrogen and soluble protein but lower lignin and cellulose contents than barnyard grass. Together, these results suggest that volatile emissions, specific non-volatile nutritive and defensive chemicals may have close correlations with trade-offs of the adult preference and larval performance between these two hosts. As developing chemical-based technology is one of the main approaches for the control of pest insects, our findings may also contribute to the future efforts for management of the rice water weevil.

Continuum mechanics break down in bending stiffness calculations of mono- and few-layered two-dimensional (2D) van der Waals crystal sheets, because their layered atomistic structures are uniquely characterized by strong in-plane bonding coupled with weak interlayer interactions. Here, we elucidate how the bending rigidities of pristine mono- and few-layered molybdenum disulfide (MoS2), graphene, and hexagonal boron nitride (hBN) are governed by their structural geometry and intra- and inter-layer bonding interactions. Atomic force microscopy experiments on the self-folded conformations of these 2D materials on flat substrates show that the bending rigidity of MoS2 significantly exceeds those of graphene or hBN of comparable layers, despite its much lower tensile modulus. Even on a per-thickness basis, MoS2 is found to possess similar bending stiffness to hBN and is much stiffer than graphene. Density functional theory calculations suggest that this high bending rigidity of MoS2 is due to its large interlayer thickness and strong interlayer shear, which prevail over its weak in-plane bonding.

Temperature drastically determines insect abundances, thus under climate change, identifying major drivers affecting pest insect populations is critical to world food security and agricultural ecosystem health. Here, we conducted a meta-analysis with data obtained from 120 studies across China and Europe from 1970 to 2017 to reveal the roles of climate and agricultural practices in determining populations of wheat aphids. We showed aphid loads on wheat had distinct patterns between these two regions, with a significant increase in China but decrease in Europe over this time period. Although average winter and growing season temperatures increased over this period in both regions, we found no evidence showing climate warming affected aphid loads. Rather, differences in pesticide use, fertilization, land use, and natural enemies between China and Europe may be key factors accounting for differences in aphid pest populations. These findings provide insights for developing effective agroecosystem management under global change. These long-term data suggest that climate change may not be the most important driver of agricultural pest loads. Therefore, under global environmental change, consideration of multiple factors at large spatial-temporal scales will likely provide more insights for developing effective agroecosystem management to safeguard world food security.

Herbivore‐induced changes in plant volatile emissions mediate above–below‐ground interactions by determining host plant colonization of different herbivores. By changing shoot‐emitted volatiles, below‐ground herbivores may use the plant to extend their capacity to interact with above‐ground con‐ and heterospecifics. We investigated the attractiveness of Triadica sebifera plants infested by larvae of a specialist beetle or root‐knot nematodes to above‐ground herbivores. We then determined the contribution of leaf volatiles to the observed recruitment patterns using olfactometer experiments. We also identified volatiles through gas chromatography–mass spectrometry (GC–MS) and electroantennography, and conducted field experiments to confirm their effects. Leaf volatiles induced by the root‐feeding larvae attracted above‐ground conspecific adults in laboratory and field experiments, but repelled a heterospecific specialist weevil, whereas induction by root‐knot nematodes had no effects on either. Greater leaf consumption by conspecific adults increased root nutrients, decreased root defences and facilitated root feeding larval performance. Thus, larvae and adults appear to manipulate their host plant, which increases aggregation above‐ground and feeding below‐ground. Synthesis. The resulting colonization dynamics may shape the composition of plant rhizosphere and phyllosphere herbivore communities by enhancing conspecific establishment and reducing colonization by other herbivores. By modifying above‐ground volatiles and above‐ground herbivore behaviour, root feeders could mediate plant and leaf herbivore interactions and benefit via plant responses to above‐ground feeding.

Hydraulic fracturing and self-diverting acid based on viscoelastic surfactant are effective methods to improve the production of low permeability reservoirs. However, surfactants as the main agents of the fluids have a certain impact on oil and gas exploration. The adsorption of surfactant on the rock may change the hydrocarbon flow path and greatly influence the recovery rate. This plagues people in choosing surfactant in reservoir stimulation. In order to make people have a clearer understanding of this issue, we synthesized four representative quaternary ammonium surfactants, including single/Gemini -cationic surfactant and single/Gemini zwitterionic surfactant. The critical micelle concentration (CMC), the adsorption and wettability were researched. The adsorption mechanism of viscoelastic surfactants was investigated through the static adsorption properties and wettability studies of different types of viscoelastic surfactants on carbonate rocks and sandstones with varying concentrations and temperatures. This has important guiding significance for choosing surfactants in the reservoir stimulation.

A new dibenzylamine-quinoline derivative (DEEQ) was synthesized and investigated as a corrosion inhibitor for mild steel in 15% HCl solution in various ways, including via weight loss measurements, contact angle measurements, electrochemical measurements (EIS), scanning electron microscopy (SEM), scanning Kelvin probe (SKP) and theoretical calculations. The experimental results revealed that DEEQ is an effective corrosion inhibitor for oil and gas acidification. In an oil–water two-phase system, the wettability of mild steel can be changed by adsorption, while obeying the Langmuir adsorption isotherm. Finally, quantum chemical calculations and molecular dynamic simulation parameters further show a definite correlation between the theoretical and experimental results.

Herbivores use plant chemicals for host-plant selection to maximize their own and/or offspring performance. Since host plants that are optimal for mother and offspring are often different and spatially/temporally separated, how plant chemicals affect trade-offs between adult preference and larval performance remains unclear. We found that adults of the rice water weevil (Lissorhoptrus oryzophilus), one of the most important pests on rice in the world, preferred volatiles from barnyard grass over rice, tended to feed and oviposit on barnyard grass compared with rice. In contrast, larvae performed better on rice roots than on barnyard grass roots. Chemical analysis further show that rice roots had higher nitrogen and soluble sugar but lower lignin and cellhouse contents than barnyard grass. Together, these results suggest that violate, nutritive and defensive chemicals could jointly determine trade-offs of the adult preference and larval performance on these two hosts. As developing chemical-based technology is one of the main approaches for control of pest insects, our findings may also contribute to the future efforts for management of the rice water weevil.

Understanding how host plant chemistry affects invasive insects is crucial for determining the physiological mechanism of host use and predicting invasive insect outbreak and damage on hosts. Here, we examined the effects of plant nutrition and defensive chemicals on host preference and performance of adults and larvae of the invasive potato tuberworm, Phthorimaea operculella (Zeller; Lepidoptera: Gelechiidae), on four native (Solanum tuberosum, Nicotiana tabacum, Datura stramonium, and Solanum lycopersicum) and three new (Solanum melongena, Physalis alkekengi, and Lycium barbarum) host plants. We found that adults preferred to oviposit on S. tuberosum and N. tabacum leaves and the soil around these native host plants over other hosts. Larvae performed well on S. tuberosum and N. tabacum, reaching higher pupa weight and having better survival. Larvae performed poorly on S. melongena, S. lycopersicum, P. alkekengi, D. stramonium, and L. barbarum, with lower pupa weight and lower survival. Solanum tuberosum and N. tabacum had higher leaf soluble proteins than other plants and lower leaf total phenolics than S. lycopersicum, D. stramonium, and L. barbarum. Moreover, carbon content and soluble protein were positively associated with larval survival, while defensive traits (lignin and total phenolics) negatively affected larval survival. These findings provide insights into understanding of biochemical mechanisms of interactions between invasive insects and host plants, indicating the importance of considering plant chemistry when assessing invasive insect host use and damage.

Conspecific aboveground and belowground herbivores can interact with each other, mediated by plant secondary chemicals, however, little attention has been paid to the interaction between leaf feeders and tuber-feeders. Here, we evaluated the effect of the foliar feeding of P. operculella larvae on the development of conspecific larvae feeding on harvested tubers by determining the nutrition and defense metabolites in the whole plant (leaf, root and tuber). We found that leaf feeding negatively affected tuber larval performance by increasing the female larval developmental time and reducing the male pupal weight. In addition, aboveground herbivory increased &alpha, chaconine and glycoalkaloids in tubers and &alpha, solanine in leaves, but decreased &alpha, chaconine and glycoalkaloids in leaves. Aboveground herbivory also altered the levels of soluble sugar, soluble protein, starch, carbon (C), nitrogen (N), as well as the C:N ratio in both leaves and tubers. Aboveground P. operculella infestations could affect the performance of conspecific larvae feeding on harvested tubers by inducing glycoalkaloids in the host plant. Our findings indicate that field leaf herbivory should be considered when assessing the quality of potato tubers and their responses to pests during storage.

As we know that hydraulic fracturing as a major method has gained great attention in developing the unconventional oil and gas resources in the past decades. Since the unconventional reservoir is very complex and the success of fracturing operation depends largely on the performances of the fracturing fluid, a good fracturing fluid such as a low carbon hydrocarbon non-aqueous fracturing fluid can be a good solution to these problems. A non-aqueous fracturing fluid with good performance was obtained in the presence of main agent aluminum sulfate, aluminum chloride or aluminum nitrate. The reaction time, temperature, material ratio and crosslinking ratio were carefully screened to match the new dialkyl phosphate in a base fluid of n-pentane or n-hexane via cross-linking to prepare a novel type of low carbon hydrocarbon non-aqueous fracturing fluid for unconventional reservoir. This fracturing fluid system performed excellent heat and shearing resistance, and could maintain high viscosity at high temperature (120–167 °C), which could be further proved by the clear structure of microscopic three-dimensional network. Finally, the fracturing fluid could be broken quickly without any residue. It can be seen that such features make it potentially economic, useful and practical as an alternative technology, especially under the condition of water shortage.

Chitosan is a widely distributed recyclable green resource in nature. Because of the particular molecular structure, chitosan derivatives have become an effective way to research environmental friendly corrosion inhibitors for oil and gas well acidizing. In this study, four chitosan derivatives were synthesized and investigated as green corrosion inhibitors for P110 steel in 15% HCl solution in various ways, including weight loss, scanning electron microscopy (SEM), electrochemical measurements (EIS), energy dispersive spectrum (EDS) and molecular dynamic simulations. The experimental results demonstrate that four chitosan inhibitors have an excellent inhibition effect, and there is an obvious negative correlation between the concentration of corrosion inhibitor and the inhibition efficiency. Finally, the erosion effect of the fluid on the corrosion inhibitor layer was studied under different flow velocity conditions and pipeline positions in oil and gas well. The results reveal that the erosion effect of the pipe is proportional to the inlet velocity of the fluid.

Sulfur deposition attracts great attention for the exploration of oil and gas and is considered one of the most important hazardous processes in China, and all over the world. Thus, investigating a sulfur solvent is absolutely necessary and highly desirable in the sour gas reservoir development. In recent years, various sulfur solvents were developed and applied in different oilfields. However, they have disadvantages in their practical applications. In this paper, a solution is proposed to solve the problem and improve the sulfur dissolving ability. Three types of sulfur solvents were prepared, all of which have their own characteristics and advantages in different cases and compared with the existing sulfur solvents under the same conditions. The solubility of Dimethyl disulfide(DMDS)-based sulfur solvent system was up to 202.8 wt% at room temperature and 1020.0 wt% at 90 °C. Amine solvent systems also achieved high sulfur solubility. The solubility of diethylene triamine-ethanolamine solvent system could reach 79.6 wt% at room temperature and 210.0 wt% in 90 °C. It was shown that a more efficient sulfur solvent system can be achieved by remixing with suitable additives. This paper focuses on a preliminary study of optimizing effective sulfur solvents in order to solve the problems caused by sulfur deposition. In the long run, this may revolutionise the process of exploration, transportation and refining of crude oil or natural gas. Microscopic analysis by Scanning Electron Microscope (SEM) was used to facilitate understanding the mechanism of sulfur dissolution in each system and their differences.

As the hydraulic fracturing technologies are not conducive to the stimulation of unconventional reservoirs and too much water was consumed by the conventional hydraulic fracturing fluid, a waterless low hydrocarbon fracturing fluid system was developed as an alternative way in the view of sustainable development and energy boom. It is noteworthy that this novel system was found to exhibit excellent heat and shear resistance, while maintaining high viscosity at high temperature (up to 150 °C). In order to reduce the cost, the low carbon hydrocarbon phosphate gelling agent was prepared via the reaction of triethyl phosphate (TEP), phosphorus pentoxide (P2O5) and single alcohol, which is quite different from the reported phosphates using mixed alcohols. In addition, a ferric-complex cross-linking agent was acquired which contains main agent, complexing agent, phase transfer catalyst (PTC) and crosslinking accelerator of crosslinking agent. The rheology of low-carbon hydrocarbon non-aqueous fracturing fluid system was tested. Furthermore, gel structure could be directly observed by scanning electron microscopy, which could explain its good performance.

Novel surfactants were synthesized and investigated as green corrosion inhibitor for mild steel in 15% HCl solution in various ways including weight loss, electrochemical measurements, scanning kelvin probe (SKP), scanning electron microscope (SEM) and theoretical calculations. The efficiency of the inhibitors against the corrosion of mild steel in the aggressive solution (15% HCl) were evaluated gravimetrically at various temperatures. The corrosion inhibition efficiency (η) has been increased with the increase of the inhibitor concentration, the maximum η achieved was equal to 98.97 at temperature 90 °C. The experiments results reveal that two surfactants were effective corrosion inhibitor, and because of the amphiphilic nature of surfactant molecules, the inhibitors can be adsorbed onto mild steel surface, obeying the Langmuir adsorption isotherm. Finally, Theoretical calculation parameters of quantum chemical calculation and molecular dynamic simulations further showing a definite correlation between the theoretical and experimental results.

We reported a highly effective Pd-catalytic system for the synthesis of diarylbenzenes through Suzuki-type reaction between equal amount of diiodoarenes and arylboronic acids. This preferential oxidative addition resulted in such high selectivity.

A category of gemini surfactants with novel structures were designed and synthesized as thickening agents of clean fracturing fluids in this research. The desired products were characterized by high resolution mass spectrometry (ESI-HRMS) and infrared spectrometry (FT-IR GX). Fluid samples with a formula of 5 wt% of products and 1 wt% of KCl were evaluated. The SEM studies revealed a good network microstructure and obvious viscoelasticity, which is favorable for a proppant suspension. Furthermore, the evaluation of their rheological properties at high temperatures revealed good thermal stabilities of these fluids up to 139 °C, particularly for VES-M (the spacer for the surfactant using methylamine and epoxy chloropropane). Comparative analysis of the rheological properties showed that since long chains of N-substituents in the middle of the molecules could enhance steric hindrance and rigidity, it is unfavorable for molecular entanglement and increases the viscosity of the VES aqueous solution. Proppant-support and gel breaking evaluations were also performed. It can be seen that nearly 100% proppant suspension was observed for 180 min at ambient temperature and complete gel breaking was achieved.

Pd-catalyzed direct oxidative olefination of arenes with olefins via C–H activation is described in the absence of any chelating directing groups. For Pd-catalyzed oxidative coupling between arenes and allyl acetate, it was observed the retention of the leaving group.

Formaldehyde dehydrogenase (FDH) is a member of the zinc-containing medium-chain alcohol dehydrogenase family which oxidizes toxic formaldehyde to formate using NAD(+) as an electron carrier. Three-dimensional structures have been reported for FDHs from several different species. Most FDHs are dependent on glutathione for catalysis, but the enzyme from Pseudomonas putida is an exception. In this structural communication, the recombinant production, crystallization and X-ray structure determination at 2.7 Å resolution of FDH from P. aeruginosa are described. Both the tetrameric assembly and the NAD(+)-binding mode of P. aeruginosa FDH are similar to those of P. putida FDH, which is in good agreement with the high sequence identity (87.97%) between these two proteins. Preliminary enzymatic kinetics studies of P. aeruginosa FDH also revealed a conserved glutathione-independent `ping-pong' mechanism of formaldehyde oxidization.

Herein, we report a new "On-On" strategy based on the assembly and disassembly of fluorescein isothiocyanate nanoparticles (FITC-NPs) for sequential detections of glutathione (GSH) and caspase-3 (Casp3) with a multifunctional fluorescent probe 1. Theoretical investigations revealed the underlying mechanism that satisfactorily explained experimental results of such consecutive enhancements of fluorescence. Using this probe, we also successfully imaged the Casp3 activity in apoptotic cells.

In order to resolve the resonance problem of jack-up riser with drill string, the frequency equation of natural transverse vibration with compressive axial load and the length of the riser above the seabed as independent variable was derived in this paper. Then the frequency equation was solved by the Newton method, and the accuracy of the frequency calculation method without axial load was analyzed. In addition, a resonant rotating speed table of top-drive system (TDS) was made according to the relationship between rotating speed and frequency. The results show that: the method proposed in this paper is more accurate than the Rayleigh method; equation(22) is available when the length of the riser above the seabed is shorter than 30 meters while axial weight less than 90 tons ; there is a nonlinear relationship between the frequencies of the riser and the length of the riser above the seabed, and the frequencies decrease with the increasing length; under the general working conditions of jack-up , the relationship between the frequencies of the riser and axial compressive load is almost linear, and the frequencies decrease with the increasing axial compressive load; the resonant frequency range of the riser with drill string depends on the length of the riser above the seabed, and the resonant frequency range is extended by the increasing length.

DWDM distributed feedback laser diodes from 1540nm to 1560nm were manufactured on one single wafer by novel high throughput, low cost nanoimprint lithography (NIL). Thirteen ITU channels of 200GHz spacing are obtained. The process includes two main steps: first, step flash imprint lithography (SFIL) was used to reduce the cost of a large stamp. Then soft stamps were applied to improve imprint uniformity on a large area. Errors were analyzed and tolerances to DFB-LD performance have been simulated.

Gratings of distributed feedback laser diodes (DFB LDs) have been successfully manufactured by nanoimprint lithography (NIL). Uniform gratings with periods of about 240 nm and phase-shifted in the center have been fabricated by a soft press NIL employing a polymer stamp technology. Moreover, the shape of the grating is rectangle, rather than sinusoidal by holography. The test results show good characteristics of the electrical and spectral output. The results of this study indicate that NIL has high potential for the manufacture of DFB LDs.

A convenient method for synthesizing α-(1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonyl)methane derivatives, 3 and 4, by the well known Knoevenagel reaction, in one step, is described. The two chromophores are stilbene-type chromophores containing the same D-π-A structures and end-capped with aromatic group as their donors. Measured with femtosecond multipass Ti:sapphire amplifier as irradiation source (pumped by the laser at 800 nm), the two chromophores show efficient two-photon induced orange red fluorescence emission. The experimental results indicate that the numbers of branches of the two chromophores affect their one-photon properties and two-photon up-conversion emission behaviors, and with the increasing numbers of branches, their wavelengths of λabsmax, λspfmax and λtpfmax exhibit bathochromic shifts.

Presently, international oilfields mainly adopt hydraulic fracturing technology to stimulate the oil and gas production. However, the conventional hydraulic fracturing technology is always faced with the problem of large amount of water consumption and related pollution after fracturing, and it is not conducive to the development of unconventional oil and gas reservoirs. So the application of conventional hydraulic fracturing technology is greatly limited. The waterless hydraulic fracturing technology can effectively solve the above problems. But the application of waterless hydraulic fracturing technology is less, and the theoretical research is relatively short in China where the reserve of unconventional oil and gas resources is abundant with the relative lack of water resources. If the technological difficulties of non-aqueous fracturing fluids can be broken through, then non-aqueous fracturing fluid technology will bring significant economic and environmental benefits to the development of unconventional oil and gas resources in China. Based on the investigation of the domestic and foreign data, this paper introduces the research status on non-aqueous fracturing fluid technology and analyzes several commonly used fracturing fluid technologies. This article mainly introduced the characteristics of several kinds of waterless fracturing fluids technical, such as carbon dioxide fracturing fluid, alcohol based fracturing fluid and hydrocarbon fracturing fluid, including their strengths and weaknesses. The working mechanism of liquid CO2 fracturing fluid, supercritical CO2 fracturing fluid, alcohol based fracturing fluid, oil based fracturing fluid and low carbon hydrocarbon fracturing fluid is also studied in the paper. Finally, this paper summarizes the key points in research direction and the key problems in the application of the waterless fracturing fluid. The paper can provide some reference value for the theoretical research and practical application of the waterless hydraulic fracturing.

The specific heat of the doped blue bronzes Tl0.3-xKxMoO3(x = 0.06, 0.15) has been measured in the temperature range between 100 and 220 K. Anomalies were observed at 165.7 K and 164.8 K for Tl0.24K0.06MoO3and Tl0.15K0.15MoO3, respectively. The specific heat jump, and the entropy and enthalpy changes associated with the CDW phase transition are estimated. The results suggest that the Peierls phase transition is of second order. By analogy with the behavior of pure Tl0.3-xMoO3, it shows that in the quasi-one-dimensional blue bronze, the perfect order of the interlayer alkali or thallium polyhedral chain plays an important role in the Peierls phase transition.

Temperature dependence of Ohmic resistance, and nonlinear current–voltage (I–V) characteristics at 77 K were systematically studied in pure potassium blue bronze K 0.3 MoO 3 and Na-doped alloy bronzes K 0.3-x Na x MoO 3(x = 0.02, 0.05, 0.10). No considerable influence of Na ions doping in K 0.3 MoO 3 was found on the Peierls transition temperature, while obvious enchancement on semiconductor gap and remarkable influence on the first threshold field were observed. We attribute the first phenomenon to two opposite effects of Na ions, and the depinning model is proposed to account for the latter. The analytical form of nonlinear charge-density wave current I CDW in a moderate field range fits the power-law relation, i.e. I CDW ∝ (V/V T -1)α, where the exponent α is about 3/2 and slightly enhanced by Na ions doping.

As a member of zinc-containing medium-chain alcohol dehydrogenase family, formaldehyde dehydrogenase (FDH) can oxidize toxic formaldehyde to less active formate with NAD(+) as a cofactor and exists in both prokaryotes and eukaryotes. Most FDHs are well known to be glutathione-dependent in the catalysis of formaldehyde oxidation, but the enzyme from Pseudomonas putida is an exception, which is independent of glutathione. To identify novel glutathione-independent FDHs from other bacterial strains and facilitate the corresponding structural and enzymatic studies, high-level soluble expression and efficient purification of these enzymes need to be achieved. Here, we present molecular cloning, expression, and purification of the FDH from Pseudomonas aeruginosa, which is a Gram-negative pathogenic bacterium causing opportunistic human infection. The FDH of P. aeruginosa shows high sequence identity (87.97%) with that of P. putida. Our results indicated that coexpression with molecular chaperones GroES, GroEL, and Tig has significantly attenuated inclusion body formation and improved the solubility of the recombinant FDH in Escherichiacoli cells. A purification protocol including three chromatographic steps was also established to isolate the recombinant FDH to homogeneity with a yield of ∼3.2 mg from 1L of cell culture. The recombinant P. aeruginosa FDH was properly folded and biologically functional, as demonstrated by the mass spectrometric, crystallographic, and enzymatic characterizations of the purified proteins.

Nano-devices are increasingly required, the fabrication cost of nano-devices is quite high due to high resolution requirement. Nanoimprint lithography(NIL) is a promising technology for nano devices fabrication due to its low cost and high resolution. However, it still suffers from the large area uniformity and imprint defects problems. Herein, temperature-pressure variation soft press process are used in Simultaneous Thermal and UV (STU) imprint to enhance the uniformity and quality of pattern. This method is used to pattern high quality photonic crystals and gratings.

Based on innovative nano-optical structures and design, an embedded metal-wire nanograting was fabricated for using as a broadband polarizer or polarizing beam splitter to reflect TE-polarized light and transmit TM-polarized light, and AR coating was designed in order to achieve best efficiency for both polarizations. An upper-cladding layer of the same material as the gratings is deposited on the ridge of the gratings, whereas the metal wire is deposited in the grating trenches. This embedded structure makes the grating firmer in its applications. By optimization of the designed structure and AR coating, high polarization efficiency and low insertion loss with a broad wavelength ranges 1000-2000 nm and a wide angular tolerance are obtained.

In this paper, we report the high-temperature uncooled and high-speed directly modulated 1.3μm wavelength AlGaInAs/InP MQW-DFB ridge waveguide laser diodes. By optimizing the structure of active region based on AlGaInAs strained MQW, and the design of DFB grating, such as the position, coupling coefficient and the detuning with respect to the material peak gain, we have successfully fabricated high-speed and uncooled 1.3μm DFB laser diodes. Large bandwidth of 15GHz was achieved at room temperature. Large characteristic temperature of 80K and small degradation of slope efficiency of 1.2dB from 25°C to 85°C have been realized.

We successfully fabricated the angled strip DC-PBH style SLED devices by using low damage ICP dry etching technology. The mesa of DC-PBH SLED was formed by Cl 2 /N 2 ICP dry etching process. The low DC bias (

This paper summarizes the recent advances and results of uncooled, high-speed directly modulated long-wavelength DFB laser diodes. It discusses ways of obtaining high temperature operation of laser diodes. By assessing the effect of carrier transport, doping and strain in active region, as well as the non-active region factor, such as laser waveguide properties and microwave parasitic parameters, various methods are discussed to improve the direct modulation bandwidth.

A 1.3-\mu m wavelength vertical-mesa ridge waveguide mulitple-quantum-well (MQW) distributed feedback (DFB) laser with high directly modulated bandwidth and wide operation temperature range is reported. With the optimization of the strained-layer MQWs in the active region, the surrounding graded-index separated-confinement-heterostructure waveguide layers, together with the optimization of the detuning and coupling coefficient of the DFB grating, high directly modulation bandwidth of 16 GHz at room temperature and wide working temperature range from ?40 to 85 \circ C are obtained. The mean time to failure (MTTF) is estimated to be over 2×10lsupg6l/supg h. The device is suitable as light source of high-bit-rate optical transmitters with small size and reduced cost.

In this paper, an embedded metal-wire nanograting was fabricated and used to construct a multifunctional optical device. The basic function of the nanograting is as a broadband polarizing beam splitter. On the top of the nanograting surface, a homogeneity cladding layer was deposited, and metal wires were deposited in the grating trench. This multifunctional optical device based on the artificial material is designed with a very simple structure, but with the functions of a variable optical attenuator, an optical switch, and a variable optical power splitter. The experimental result as a variable optical power splitter is presented.

What we believe to be a new type of embedded metal-wire nanograting is fabricated, in which the metal wires are embedded under the trenches of the substrate, and a cladding layer is deposited on the surface of the trenches to protect the metal-wire grating. The substrate of the nanograting is antireflectively coated to further increase the performance of the device. This novel embedded nanograting has a high extinction ratio, low insertion loss for optical communication wavelengths, and good wearability for practical applications. This kind of metal-wire nanograting is attractive as a polarizing beam splitter or combiner to construct various optical devices. By using this newly developed kind of nanograting, a polarization beam splitter/combiner with good performance is fabricated.