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This study aimed to investigate the regulatory function of lncRNA RMRP in non-alcoholic fatty liver disease (NAFLD). In vitro and in vivo NAFLD models were constructed. Hematoxylin & Eosin (H&E) and Oil-Red O staining assays were conducted to observe the morphology and lipid accumulation in liver tissues. Triglycine (TG) secretion was detected by ELISA assay. The expression levels of RMRP, microRNA-206, PTPN1 (protein tyrosine phosphatase, non-receptor type 1), and their downstream genes were assessed by qRT-PCR and Western blot. The regulatory relationship among these molecules was determined by luciferase reporter and RNA pull-down assays. RMRP and PTPN1 were up-regulated, while miR-206 was down-regulated in the liver tissues of NAFLD patients and rat model. RMRP inhibition improved the pathological state and liver function-related indexes of liver lipid deposition in the liver tissues of NAFLD rats. RMRP inhibition alleviated steatosis and TG secretion in free fatty acids (FFA)-treated AML-12 cells. RMRP could bind to miR-206 and downregulate its expression. Meanwhile, RMRP inhibition attenuated lipid accumulation by downregulating the PTPN1-PP2ASP1-SREBP1C pathway. Furthermore, RMRP inhibited the miR-206/PTPN1-SREBP1C signaling pathway in NAFLD rats and FFA-treated AML-12 cells. RMRP inhibition prevented NAFLD progression in rats via targeting the miR-206/PTPN1 axis. [ABSTRACT FROM AUTHOR]

Achieving uniform dispersion of nanofillers in a polymer matrix, particularly for incompatible compounds, remains a formidable challenge. In this study, thermally reduced graphene oxide (TrGO) sheets were effectively dispersed within a nonpolar polypropylene (PP) matrix using a two-step approach, leveraging the Friedel–Crafts reaction catalyzed by AlCl 3. The results showed that the size and number of TrGO aggregates were significantly reduced after AlCl 3 treatment. The thermo-oxidative stability in terms of oxidation induction time (OIT) of the PP/TrGO(Al) composite further improved by 2 times when 0.1 wt% TrGO was added to the PP matrix compared with that of the samples without AlCl 3 treatment. The improved thermo-oxidative stability and mechanical properties of PP/TrGO(Al) can be attributed to its superior radical scavenging efficiency, oxygen barrier effect, and effective load transfer afforded by the excellent dispersion of TrGO. This research highlights a pioneering methodology for enhancing both the dispersion of TrGO in a nonpolar polymer matrix and the thermo-oxidative resilience of the resultant composites. [Display omitted] • TrGO sheets were well-dispersed in PP matrix by using a two-step method through Friedel-Crafts reaction. • The thermo-oxidative stability of PP/TrGO(Al) composite were further improved due to the improvement of TrGO dispersion. • This can be attributed to the radical scavenging ability and oxygen-barrier effect of well-dispersed TrGO. [ABSTRACT FROM AUTHOR]

• Constant compressive stress promoted the fracture of polysulfide and disulfide bonds. • Reactive sulfur-containing side (RSS) groups were formed under compressive stress. • RSS groups could participate in re-crosslinking reactions in the presence of heat. • RSS groups increased the hysteresis loss of NR under deformation. The evolution process of the crosslinking structure in sulfur-cured natural rubber (NR) under the combined effect of compressive stress and temperature was investigated using a homemade constant-stress device. The aged NR samples were characterized by infrared spectroscopy, chemical probe method, differential scanning calorimetry, and mechanical analysis. The results revealed that compressive stress promoted the breakage of sulfur bonds (mainly low-energy ones) between NR chains, leading to a decline in crosslink density and an increase in mesh size. According to the Arrhenius equation, a compressive stress of 1.78 MPa reduced the apparent activation energy for the breakage of polysulfide bonds from 56.3 kJ/mol to 48.2 kJ/mol, resulting in a 14.4% decrease. The sulfur-containing side groups formed after the breakage of polysulfide bonds not only participated in post-crosslinking reactions after stress release but also increased the hysteresis loss of NR under large deformation. [ABSTRACT FROM AUTHOR]

We propose a new kind of distributed feedback (DFB) semiconductor laser based on the sampled Moiré grating (SMG) integrated with a grating reflector (GR). Coupling coefficient along the laser cavity can be controlled, and $\pi $ phase shift ($\pi $ -PS) can be introduced by SMG. The GR, which is a uniform sampled grating, can provide light reflection instead of high reflection (HR) facet coating. Thus, the front and rear facets are both coated with anti-reflection coatings (AR/AR) to avoid the influence of random grating phase at the HR facet. Therefore, more output power, better single longitudinal mode (SLM) operation, and higher wavelength precision can be simultaneously achieved, compared with traditional DFB lasers with AR/HR facet coatings. As an example, an 8-channel DFB laser array based on the proposed structure has been simulated. The proposed laser may benefit the applications requiring both high output power and wavelength precision, such as wavelength division multiplexing (WDM) transmission systems and gas sensors. [ABSTRACT FROM AUTHOR]

The a priori procedure (APP) provides minimum sample sizes to meet specifications for precision and confidence that, in turn, can enhance trust that the sample statistics to be obtained provide good estimates of corresponding population parameters. A recent advance by Chen et al.3 showed how to perform the APP with respect to Cohen's d , which is the most popular effect size measure in the social sciences. However, a limitation is that Chen et al.3 assumed normal distributions that compose only a subset of the much larger family of skew normal distributions, which are used as distributions of random errors in many economical models such as stochastic frontier models that are popular and useful models to investigate production efficiency in microeconomics, see Hung.5 Therefore, it would be useful to generalize to skew normal distributions. We perform the mathematical derivations for the generalization and support them with simulations and worked examples. Finally, we provide a free and user-friendly computer program by which researchers can perform the APP to determine minimum sample sizes necessary to meet specifications for precision and confidence, with respect to Cohen's d , for a matched sample under the large umbrella of skew normal distributions. [ABSTRACT FROM AUTHOR]

Recently, great breakthroughs in natural gas exploration have been achieved in the Nanpu Sag, Bohai Bay Basin, eastern China; however, the genetic type and formation mechanisms of the gas are still unclear, impeding further exploration. Chemical and isotopic compositions were investigated to determine the origins for the gas. Three groupings of the natural gases are recognized: oil-type gas, coal-type gas, and mixed-source gas. The oil-type gases are relatively depleted in 13 C (δ 13 C 1 < −43‰); δ 13 C 2 < −29‰ and low wetness (0.60–0.89). The coal-type gases are enriched in 13 C (δ 13 C 1 > −40‰; δ 13 C 2 > −28‰) with higher wetness (0.80–0.95). The third grouping of gases exhibits intermediate molecular and isotopic values. Most of the gases in the shallow layers of the No. 1 and 4 structural belts have δ 13 C values similar to those of underlying gases and display evidence for microbial alteration. Primary cracking of kerogen is responsible for the generation of most of this gas. Pyrolysis of the source rocks combined with maturity estimations revealed that the relatively shallow oil-type gas was derived primarily from Oligocene and Eocene (Ed 3 –Es 1 ) source rocks bearing Type I–II 1 kerogen, whereas the coal-type gas was generated from the Eocene (Es 2+3 ) source rocks containing II 2 –III kerogen. We concluded that the kerogen type and maturity of the source rocks and the activity of source-connecting faults primarily controlled the distribution of the different gases. We suggest that there is significant deep gas potential in the Nanpu Sag, perhaps even over the whole Bohai Bay Basin, that would be prospective for further deep gas exploration in the area. [ABSTRACT FROM AUTHOR]

Photonic integrated circuits (PICs) technologies in China have made rapid progress in the past decade. In this paper, recent advances and future prospective of PICs in China are introduced and discussed, respectively. More than nine major projects in the field of PICs have been issued. Various material platforms and technologies have been developed to realize photonic integrated devices for many applications focusing on broadband communication, such as optical and wireless network, optical interconnects, and optical coherent communication. Many research achievements and breakthrough have been made under the support of these projects, such as silicon photonics transceiver, InP-based transceiver, and optical and microwave signal processing chips. It can be expected that the PICs technology will be continuously supported in the next five years, since it has been considered as one of the key enabling technologies for supporting several national major assignments and strategies, such as broadband communication, supercomputing and datacenter. [ABSTRACT FROM AUTHOR]

Three new oxidovanadium(V) complexes with formula [VOLL′] (L = L 1 = N ′-(2-hydroxy-4-methoxybenzylidene)-4-hydroxybenzohydrazide for 1 , L = L 2 = N ′-(3-ethoxy-2-hydroxybenzylidene)pivalohydrazide for 2 , L = L 3 = 2-bromo- N ′-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide for 3 , L′ = ethylmaltol), have been prepared. The complexes have been characterized by physico-chemical methods and single crystal X-ray determination. The V atom in each complex is coordinated by the NOO donor atoms of L, the OO donor atoms of L′, and one oxido group, forming octahedral coordination. The complexes were administered intragastrically to both normal and alloxan-diabetic mices for two weeks. The biological activity results show that the complexes at doses of 10.0 and 20.0 mg V·kg −1 , can significantly decrease the blood glucose level in alloxan-diabetic mices, but the blood glucose level in the treated normal mices was not altered. [ABSTRACT FROM AUTHOR]

The wear damage and aging behavior of natural rubber (NR) nanocomposites are very complex under severe conditions (high load, high-speed wear, or ablation). Little is known about the influence of strong interfacial friction on the high-temperature aging mechanism in the internal of NR nanocomposites. In this study, a set of UMT-TriboLab wear tester was used to study the wear and aging of NR nanocomposites, and to reveal their influence on the internal aging of specimens under severe conditions. Sliding wear tests were carried out with rubber-metal tribopair using a Block-on-Ring configuration. Different from mild wear conditions, the wear mechanism of NR nanocomposites under severe conditions experienced a transition from abrasive wear to adhesive wear. The viscous film formed by the degradation products on the wear surface was found to strongly affect the subsequent wear and aging behavior (wear weight loss, friction coefficient, temperature rise, etc.) of specimens. Layer-by-layer analysis showed that the heat diffusion caused by surface wear resulted in noticeable post-crosslinking in the internal layer of specimens while the oxidation reaction was limited to occur only on the specimen surface. • The wear behavior of NR blocks was studied under high loads and high speeds. • The specimen surface underwent serious mechanical and oxidative degradation. • Viscous films formed at interface strongly affected the wear and aging behavior. • Diffusion of frictional heat led to post-crosslinking in the internal layer. [ABSTRACT FROM AUTHOR]

Mixed-level designs are widely used in the practical experiments. When the levels of some factors are difficult to be changed or controlled, fractional factorial split-plot (FFSP) designs are often used. This paper investigates the sufficient and necessary conditions for a $${2^{(n_{1}+n_{2})-(k_1+k_2)}4_s^{1}}$$ FFSP design with resolution III or IV to have various clear factorial effects, including two types of main effects and three types of two-factor interaction components. The structures of such designs are shown and illustrated with examples. [ABSTRACT FROM AUTHOR]

Abstract: Mixed-level designs have become widely used in the practical experiments. When the levels of some factors are difficult to be changed or controlled, fractional factorial split-plot (FFSP) designs are often used. It is highly to know when a mixed-level FFSP design with resolution III or IV has clear effects. This paper investigates the conditions of a resolution III or IV FFSP design with both two-level and four-level factors to have various clear factorial effects, including two types of main effects and three types of two-factor interaction components. The structures of such designs are shown and illustrated with examples. [Copyright &y& Elsevier]

We summarized the design, fabrication challenges and important technologies for multi-wavelength laser transmitting photonic integration. Technologies discussed include multi-wavelength laser arrays, monolithic integration and modularizing coupling and packaging. Fabrication technique requirements have significantly declined with the rise of reconstruction-equivalent-chirp and second nanoimprint mask technologies. The monolithic integration problem between active and passive waveguides can be overcome with Butt-joint and InP array waveguide grating technologies. The dynamic characteristics of multi-factors will be simultaneously measured with multi-port analyzing modules. The performance of photonic integration chips is significantly improved with the autoecious factors compensation packaging technique. [ABSTRACT FROM AUTHOR]

A novel apodization technique of writing a sampled Bragg grating is presented for the first time in the paper, which uses an amplitude mask with variable duty cycle and a phase mask. This technique only needs a one-process-exposure instead of two-process-exposure to write an apodized sampled Bragg grating. The numerical simulation has been implemented and the experimental results show that this technique is efficient in reducing the side lobes in the spectrum reflection and the group delay ripples. [Copyright &y& Elsevier]

In this paper, a new implementation of the double exposure method for fabricating apodized fiber Bragg gratings by controlling the parameters of rotation stage and the number of UV-shots is presented. As a result, the average refractive index is kept nearly constant along the Bragg grating, and various apodized fiber Bragg grating with high reflectivity and high side lobe suppression ratio have been fabricated in single-mode hydrogen-loaded photosensitive fiber . The achieved side-lobe suppression ratio is larger than 25 dB. [Copyright &y& Elsevier]

Properly designed sampling function of a sampled Bragg grating can produce an equivalent chirp profile within reflection bands with non-zero Fourier orders. This method has the advantage that various equivalent chirp profiles can be achieved while the phase mask used in the fabrication process needs not to have any chirp. The principle of this method is demonstrated by the fabrication of a sampled fiber Bragg grating with a linear equivalent chirp profile using a uniform-period phase mask. [Copyright &y& Elsevier]

This paper discusses the impairment of bandwidth cutoff and group delay jump effects to eye opening penalty of chirped sampled Bragg grating dispersion compensator at 10 and 40 Gb/s theoretically. Both analytical and numerical simulation results show that bandwidth cutoff effect is the main reason for deterioration of eye opening penalty, while group delay jump effect is negligible. Cascaded transmission simulations also show that bandwidth cutoff effect does not cause the penalty deterioration apparently when span number increases. [Copyright &y& Elsevier]

We present a microsphere-based microsensor that can measure the vibrations of the miniature motor shaft (MMS) in a small space. The microsensor is composed of a stretched fiber and a microsphere with a diameter of 5 μm. When a light source is incident on the microsphere surface, the microsphere induces the phenomenon of photonic nanojet (PNJ), which causes light to pass through the front. The PNJ's full width at half maximum is narrow, surpassing the diffraction limit, enables precise focusing on the MMS surface, and enhances the scattered or reflected light emitted from the MMS surface. With two of the proposed microsensors, the axial and radial vibration of the MMS are measured simultaneously. The performance of the microsensor has been calibrated with a standard vibration source, demonstrating measurement errors of less than 1.5%. The microsensor is expected to be used in a confined space for the vibration measurement of miniature motors in industry. [ABSTRACT FROM AUTHOR]

Real-time online identification of spacecraft segment damage is of great significance for realizing spacecraft structural health monitoring and life prediction. In this paper, a damage response characteristic field inversion algorithm based on the differential reconstruction of strain response is proposed to solve the problem of not being able to recognize the small damages of spacecraft structure directly by the strain response alone. Four crack damage location identification methods based on vector norm computation are proposed, which realize online identification and precise location of structural damage events without external excitation by means of spacecraft structural working loads only. A spacecraft segment structural damage monitoring system based on fiber optic grating sensors was constructed, and the average error of damage localization based on the curvature vector 2 norm calculation was 2.58 mm, and the root-mean-square error was 1.98 mm. The results show that the method has superior engineering applicability for on-orbit service environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: In recent years, people have paid more and more attention to the health hazards caused by O 3 exposure, which will become a major problem after fine particulate matter (PM). OBJECTIVE: To investigate the effects of ozone (O 3) exposure on blood glucose levels in rats under different concentrations and times. METHODS: Eighty rats were divided into control group and three ozone concentration groups. Each group was continuously exposed for 1d, 3d and, 6d, and exposed for 6 hours daily. After exposure, GTT, FBG, and random blood glucose were measured. RESULTS: The FBG value increased significantly on the 6th day of 0.5 ppm and the 3rd and 6th days of 1.0 ppm exposure compared with the control group (P < 0.05). The random blood glucose value was significantly increased on the 3rd and 6th days of each exposure concentration (P < 0.05). When exposed to 1 ppm concentration, the 120 min GTT value of 1 d, 3 d and, 6 d was significantly higher than that of the control group (P < 0.05). CONCLUSION: After acute O 3 exposure, the blood glucose level of rats was affected by the exposure concentration and time. The concentration of 0.1 ppm had no significant impact on FBG and random blood glucose, and O 3 with a concentration of 0.1 ppm and 0.5 ppm had no significant impact on values of GTT at 90 min, and 120 min. [ABSTRACT FROM AUTHOR]

• As a natural antioxidant, NRCs improved the thermo-oxidative stability of NR. • NRCs promoted the formation of mono- and disulfide bonds during vulcanization. • More monosulfide bonds were formed during the aging of vulcanized SHANR. • SHANR showed high thermal/mechanical stability against aging. Non-rubber components (NRCs) in natural rubber (NR), including proteins, phospholipids, fatty acids, etc., determine to a large extent the structure and properties of NR. In this study, the effects of NRCs on the network structure and thermo-oxidative aging behavior of unvulcanized and vulcanized NR were investigated. NRCs were found to form physically crosslinked networks in the unvulcanized NR and acted as a natural antioxidant to scavenge free radicals, which contributed to improved thermo-oxidative stability of the unvulcanized NR. Swell analysis, chemical probe analysis (DPPH), and XPS results showed that the NRCs accelerated the vulcanization reaction and increased the crosslink density, and promoted the formation of more mono- and disulfide bonds during vulcanization. When aged at high temperatures, more monosulfide bonds were formed in the vulcanized rubber with high contents of NRCs by cleaving and rearranging the poly- and disulfide bonds. NRCs were also found to increase the activation energy of thermal degradation and led to the better mechanical stability of vulcanized NR against thermal oxidation. [ABSTRACT FROM AUTHOR]

A compact multi-wavelength hybrid-integrated directly-modulated distributed-feedback laser (DML) transmitter optical sub-assembly (TOSA) has been achieved in our laboratory. The 8-channel distributed feedback (DFB) lasers are monolithically integrated based on the reconstruction-equivalent-chirp (REC) technology. With the high-density and high-speed packaging technique, the laser array and a multi-mode interference (MMI) multiplexer are assembled in the TOSA. The channel spacing of the TOSA is 200 GHz between adjacent lasers. It meets the 8 × 12.5 Gb/s operation demand and gives rather low channel crosstalk of less than −25 dB. This compact TOSA is of effective cost and shows good stability for mass production, which is expected to improve the performance of devices in access networks, data centers and supercomputing. [ABSTRACT FROM AUTHOR]

A dual-passband microwave photonic filter (MPF) implemented based on phase-modulation to intensity-modulation (PM-IM) conversion using a phase modulator and an equivalent phase-shifted fiber Bragg grating (EPS-FBG) is proposed and experimentally demonstrated. The key component in the system is the EPS-FBG, which is designed and fabricated based on the equivalent phase-shift technique. The unique feature of the EPS-FBG is that equivalent phase shifts are introduced to both of the \pm \1^st channels, leading to a notch in each of the two channels. Thus, by implementing PM-IM conversion in the two channels, two passbands are produced. The central frequency of each passband is determined by the wavelength different between the notch and the optical carrier. In the design and fabrication, two phase shifts are introduced to the EPS-FBG to decrease the shape factor, which is defined as the ratio between the 20- and 3-dB bandwidths. In addition, a stimulated Brillouin scattering (SBS) assisted filter is incorporated in the system for carrier suppression to increase the spurious-free dynamic range (SFDR) and decrease the noise figure (NF) of the MPF. An experiment is performed. A dual passband filter with a 3-dB bandwidth and a shape factor of 167.3 MHz and 3.8, and 143.3 MHz and 3.3 for the \1^st and \2^nd passband is achieved. The frequency tunable ranges of the \1^st and \2^nd passbands are 5.4 and 7.4 GHz, respectively, with the magnitude variations of about \pm \ 0.5 dB during the turning. Due to the SBS-assisted filter, the SFDRs are increased by 7 dB and the NFs are decreased by 10 dB. [ABSTRACT FROM AUTHOR]

Metalens have the advantages of ultra-thin, low loss, easy integration and flexible phase control mechanism, which have attracted intensive attention in the field of on-chip photonic chips. By designing Si nanocylinder meta-atom on SiO 2 substrate, the structure size is optimized to achieve the optimal light transmittance and phase change covers the range of 2π. In order to achieve the effect of coupling Distributed Feedback Laser (DFB) array into a fiber, it is necessary to accurately arrange the above optimized Si nanocylinder according to a certain phase profile to achieve the effect of off-axis focusing. Here, we designed an off-axis focusing metalens array to efficiently couple the parallel 4-channel DFB laser array into the few-mode fiber (FMF), and the total coupling efficiency reaches 56.48 %. This result provides a new idea for compact, low loss on-chip light sources. • A novel and reliable low loss laser array combining scheme is proposed. • An off-axis focusing metalens array is designed for multi-channel laser combining. • The combiner has the advantages of high integration, low loss, polarization insensitivity, and mode insensitivity. • In the parallel 4-channel laser array, the metalens array exhibits a coupling efficiency of 56.48 %. • The loss of the proposed combiner does not increase with the increase of the laser channels number. [ABSTRACT FROM AUTHOR]

Chaotic optical communications provide high security for physical layer encryption. We propose a chaotic laser communication system based on a balanced detection optoelectronic delayed feedback system, which has a higher performance compared with one based on single-photodiode detection. Our numerical analysis proves that dynamic behaviors are achieved at only half feedback gain, and the safety hazard chaotic dead zone is eliminated. The generated chaos features high pseudo-randomness and a good capacity to conceal time-delay signatures, which makes it hard for an unauthorized party to remove the chaotic carriers. 10 Gbps message hidden in wideband chaotic carries is transmitted back-to-back, and the BER 10−1 of the eavesdropper achieved at a low feedback gain β=3.2 proves its high confidentiality. Our proposed system has the potential to promote chaotic laser systems to practical appliances with simple structure and high performance. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate a high-power eight-wavelength distributed feedback (DFB) laser array with 100 GHz spacing using the grating reflector (GR). The GR, which is a uniform sampled grating, can provide light reflection instead of high reflection (HR) facet coating. Thus, the front and rear facets are both coated with anti-reflection coatings (AR/AR) to avoid the influence of a random grating phase at the HR facet. Therefore, more output power, better single-longitudinal-mode operation, and higher wavelength precision can be simultaneously achieved, compared with traditional DFB lasers with HR/AR facet coatings. The maximum output power and side mode suppression ratio of the fabricated eight-channel GR-DFB laser array as high as 70 mW and 55 dB can be achieved, which may benefit wavelength division multiplexing transmission systems, gas sensors, optical computing systems, and microwave photonic signal processing. [ABSTRACT FROM AUTHOR]

An asymmetric π equivalent phase shift sampled Bragg grating (SBG) semiconductor, which is consisted of two section with the same length but different sampling duty cycle 0.4 and 0.6, is investigated experimentally. By increasing the two injected currents of the studied laser from 15 mA to 120 mA, the lasing wavelength can be tuned by 2.1 nm. Combining selecting appropriate sampling period, the lasing wavelength of the laser can be tuned to meet the ITU-T standard. Because of high yield and low cost, this type of SBG laser is very beneficial for designing and fabricating monolithically integrated wideband multiwavelength laser array for photonic integrated circuits in next generation fiber-optic system. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:692-696, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27357 [ABSTRACT FROM AUTHOR]

Based on reconstruction-equivalent-chirp technology, an equivalent \lambda/4 phase shift was introduced into the center of an asymmetric sampled Bragg grating semiconductor laser that had two sections of the same lengths but different effective refractive indices. This structure could suppress the zeroth-order channel lasing effectively and enable the laser to operate in a single longitudinal mode with high stability. Such a method can also be used to fabricate a high-quality multiwavelength laser array for enhancing the yield efficiently at reduced cost. [ABSTRACT FROM AUTHOR]

Recently space communication technology develops rapidly and space chaotic laser communication serves as an excellent scheme to enhance the security of data transmission. To achieve long-distance transmission, Erbium-doped fiber amplifier (EDFA) is used in a space chaotic laser communication system, but this will inevitably bring amplifier spontaneous emission (ASE) noise. In order to investigate the effect of ASE noise, we give a modified bit error rate (BER) calculation model and numerical simulations are conducted based on it. Quantitative results show that most of ASE noise in the system is caused by the EDFA at the receiver rather than the emitter. Apart from this, deeper researches further indicate that ASE noise will induce mismatch. When ASE noise is small, inherent mismatch noise is the main factor causing mismatch. But as ASE noise power becomes larger, mismatch noise will be dominated by external mismatch noise and internal mismatch noise. Our results have a good reference value for the design of space chaotic laser communication systems. [ABSTRACT FROM AUTHOR]

A method of engineering spectrum of mode converter based on cascaded Bragg gratings is investigated in detail. Due to the cascaded structures, the proposed mode converter owns higher design degrees of freedom comparing with mode converter based on traditional Bragg grating. Meanwhile, thanks to various light responses of gratings, conversion spectrum can be easily tailored by designing grating structures. As examples, mode converters with specific conversion spectra such as single-band pass, double-band pass, multi-band pass, narrow-band backward spectra have been designed. Besides, the same triangle-shaped band pass spectrum is obtained by two converters based on different grating structures with the aid of distribute-layer-peeling algorithm, which further shows the high design flexibility of the proposed method. We think the proposed method gives a new way for advanced mode converter with required conversion spectrum. [ABSTRACT FROM AUTHOR]

We proposed a new kind of add-drop multiplexer based on $\pi $ phase-shifted antisymmetric Bragg grating ($\pi $ -ASBG). Light resonance is formed in the $\pi $ -ASBG with mode conversion between backward fundamental transverse electric (TE0) mode and the forward first order transverse electric (T1) mode. With the aid of the TE1 mode generated in the $\pi $ -ASBG, add-drop multiplexer can be designed. As examples, two multiplexer structures based on single- and dual-bus resonator, on silicon-on-insulator (SOI) platform have been studied in detail. Besides, no light is reflected to the input port, if the structure is carefully designed with critical coupling condition satisfied. For the fabricated add-drop multiplexer based on single-bus resonator, the extinction ratio is 23.90 dB and full width at half maximum (FWHM) is 0.33 nm at the through port. For the fabricated add-drop multiplexer based on dual-bus resonator, the extinction ratio is 17.22 dB and FWHM is 0.29 nm at through port. The results show that proposed structures provide a new method to realize add-drop multiplexer and other integrated optical filters for optical communications and sensors. [ABSTRACT FROM AUTHOR]

A novel fiber grating structure is proposed for the purpose of dispersion compensation. This kind of grating can be produced with a large chirp parameter and period sampled distribution along the grating length. There are multiple channels in the wide bandwidth and each channel has totally different dispersion and bandwidth. The dispersion compensation effect of this special designed grating is verified through system simulation. [Copyright &y& Elsevier]

We have developed and demonstrated a novel technique to manufacture large bandwidth grating with a nearly arbitrary transmittivity profile. The technique is based upon scanning the large chirped phase mask and controlling of the reflective index modulation distribution along the grating length. [Copyright &y& Elsevier]

Numerical results show that only apodization compensation is necessary for apodized binary sampled Bragg grating, while sampling compensation is not necessary. A novel off-coherent zone preconditioning approach is proposed which does not require to remove the phase mask. Experiments demonstrate the apparent improvements in the quality of reflectivity and group delay spectrum. [Copyright &y& Elsevier]

We propose a novel solution for linearly tunable polarization mode dispersion (PMD) compensation by sampled Bragg gratings fabricated with uniform-period phase masks. This all-fiber PMD compensation technique is cost-effective and flexible in designing the differential group delay (DGD) profile. Based on numerical simulations, the efficiency of this PMD compensator is assessed for the 10 Gb/s NRZ transmission system with large DGD. With this compensator, a significant improvement can be achieved in the eye pattern of the received signal. [Copyright &y& Elsevier]

Multi-wavelength distributed feedback laser array (DFB-MLA) based tunable semiconductor lasers have been widely used owing to the high mode stability and simple wavelength tuning scheme. In this paper, we proposed and experimentally demonstrated a matrix-grating tunable DFB laser array. And the reconstruction-equivalent-chirp (REC) technique is utilized to simplify grating fabrication and realize precise control of the grating phase. Traditionally, the laser is tuned by thermal-electric cooler (TEC), with large power consumption, slow wavelength tuning capability, and added device. To improve the wavelength tuning speed of laser, we varied laser’s injection current instead of adjusting TEC’s temperature. In addition, we analyzed the thermal influence of submount on the laser and then chose the SiO2 as the submount material for its low thermal conductivity and poor heat dissipation, resulting in wide wavelength tuning range via injection current. The DFB-MLA chip achieves a better tunable effect as the lasers can be tuned at 3.5–3.7 nm per channel from 50 to 120 mA with stable output power of over 3 mw as contrasted with the laser on the AlN submount being tuned at 1.4–1.5 nm per channel. And the chip has a side-mode suppressing ratio (SMSR) of over 35 dB and strong stability of wavelength in the repeated experiments. The proposed method may give a new way to realize the wide tuning range tunable DFB laser with a simple wavelength tuning mechanism in the future, especially for the applications of uncooled low-cost tunable lasers. [ABSTRACT FROM AUTHOR]

A directly-modulated Fourier domain mode-locked optoelectronic oscillator (FDML_OEO) based on three-section mutual-injection integrated semiconductor laser (TS_MIISL) with dual-loop feedback structure is proposed and experimentally demonstrated in this paper. By driving the TS_MIISL to work under the period-one (P1) state and modulating the TS_MIISL with low-repetition-rate sawtooth drive signal, a linear frequency-modulated (LFM) signal can be generated. Through adjusting the delay time of the feedback loops to match with the time duration of drive signal, the LFM signal can be significantly optimized in terms of spectral purity. In such a proposed FDML_OEO, no external modulator, polarization controller (PC) and filter are utilized, leading to an outstanding advantage in terms of stable performance and compact structure. The high-purity LFM signal with center frequency and bandwidth of 14 GHz and 8 GHz is obtained. The maximum time-bandwidth product (TBWP) of generated LFM signal could reach up to 48800. Due to the introduction of dual feedback loop, the frequency comb contrast and linewidth could reach up to 45 dB and 5 kHz, respectively. The center frequency and bandwidth of the generated signals are both tunable. A demonstration is made to prove that the pre-compensation processing could improve the linearity of LFM signals. • We have also proposed an equivalent microwave photonics filter (MPF) and it can be observed when the TS_MIISL works at P1 state. • Because of the short distance of PS between the FL and RL, the TS_MIISL would go into the short-coupling regime. • When the delay matching is completed, the spectral purity of the obtained LFM signal is significantly optimized by the optoelectronic feedback loop. • When the delay matching is completed, the spectral purity of the obtained LFM signal is significantly optimized by the optoelectronic feedback loop. [ABSTRACT FROM AUTHOR]

The grating-assisted contra-directional coupler (contra-DC) is one of the commonly used add-drop filters serving for coarse wavelength-division-multiplexing (CWDM) systems due to its flat-top and wide-band response. However, the free-spectral-range (FSR) of contra-DC is limited by the back reflection to the input port caused by the intra-waveguide coupling. In this paper we propose an anti-reflection grating-assisted contra-DC by simply increasing the sidewall corrugation width. The intra-waveguide coupling coefficient can be decreased to 0 when the corrugation width is increased to a certain value. The simulation result shows that the transmission at drop port is −0.42 dB, while the back reflection to the input port is only −22.0 dB. The 4-channel cascaded contra-DCs with wavelength range of ∼60 nm are also simulated, all the channels are not affected by the intra-waveguide coupling. We believe the proposed contra-DC with large corrugation width can be applied to the CWDM system requiring a broad spectrum range. • Explanation of the vanish of stopband when the corrugation width of waveguide Bragg grating is large. • Proposing an anti-reflection grating-assisted contra-directional coupler by simply increasing the corrugation width. • High suppression of intra-waveguide reflection in the grating-assisted contra-directional coupler of 22.0 dB. [ABSTRACT FROM AUTHOR]

To evaluate the effect of crosstalk caused by wavelength deviation of reconstruction-equivalent-chirp (REC) integrated multi-wavelength laser arrays (MWLAs) on an optical free-space communication system in which wavelength division multiplexing (WDM) is applied, we derive the model of power penalty caused by the wavelength deviation of REC-MWLAs and the bit error rate (BER) of the system under atmospheric turbulence and conduct a numerical simulation. The two adjacent channels in arranged REC laser arrays are defined as the analysis scope. We find that the power penalty is more sensitive to the deviation of the channel itself than the adjacent channel as the frequency shift increases from 0 to 50 GHz. The numerical relationship between the BER and power penalty is drawn to further investigate the tolerance for wavelength deviation under the requirements of BER < 10 − 6 and BER < 10 − 9. In addition, for a smaller deviation of 5 GHz of the analyzed channel, the linewidth compression of the REC laser can decrease the power penalty from 1.3 to 0.7 dB, improving the system performance and moderating the demands for deviation of REC-MWLAs, and the gemination of channel spacing does not evidently reduce the requirement for deviation. The results of this work demonstrate the feasibility of REC-MWLAs as the light source of WDM free-space communication systems under atmospheric turbulence and provide an effective reference for the allowable deviation in the design and testing of MWLAs. [ABSTRACT FROM AUTHOR]

With the widespread deployment of wavelength division multiplexing (WDM), optical transceivers increasingly use many glass micro-optical components (GMOC). Visual inspection of these GMOCs is a critical manufacturing step to ensure quality and reliability. However, manual inspection is often labor-intensive and time-consuming due to the transparent nature of glass components and the small, randomly located defects in three dimensions. Although automated optical inspection (AOI) exists, it has not yet been able to provide the desired level of accuracy and efficiency. This paper reports the development of an AOI platform for 3D defect detection on GMOCs. The platform incorporates 3D video acquisition and a novel two-stage neural network machine-learning algorithm. It includes a robotic arm for moving parts in 3D, a camera with an illumination module for video acquisition, and a video streaming processing unit with a machine vision algorithm for real-time defect detection on a production line. The robotic arm enables multi-perspective video capture of a test sample without refocusing. The two-stage machine learning network uses a modified YOLOv4 architecture with color channel separation (CCS) convolution, an image quality evaluation (IQE) module, and a frame fusion module to integrate the single frame detection results. This network can process multi-perspective video streams in real-time for defects detection in a coarse-to-fine manner. The AOI platform was trained with only 30 samples and achieved promising performances with a recall rate of 1, a detection accuracy of 97%, and an inspection time of 48 s per part. • In order to solve the challenging problem of defect detection on transparent optical components with 3D shape and random defect locations, a novel optical inspection platform based on video stream is developed to capture multi-perspective images of the object, and machine learning based algorithms is used to identify the defects. [ABSTRACT FROM AUTHOR]

A compact cascaded tunable distributed feedback semiconductor laser is proposed and theoretically analyzed. Each laser section (LS) is formed by two adjacent grating sections (GSs) with slightly different Bragg wavelengths and a $\pi $ phase shift in the joint between them. A step-wise grating period profile is designed to realize multi-channel lasing. Since two LSs share a common GS, the total cavity length of the tunable laser is significantly reduced. As an example, a tunable laser with six GSs and five $\pi $ phase shifts was designed and analyzed, resulting in a continuous tuning range of 12 nm. The total length of the laser is reduced by 40% compared with the conventional structure. Furthermore, an improved structure with apodized grating in each GS is also proposed. The single mode stability and fabrication tolerance are significantly improved. Due to the compact structure, the cost of the proposed laser can be highly reduced. Therefore, we think the proposed structure would benefit the practical applications to the low cost tunable lasers in wavelength-division multiplexing systems. [ABSTRACT FROM AUTHOR]

• The quarter-wavelength-shifted DFB laser is firstly reported to generate optical chaos. • Two paths of complex optical chaotic signals with a bandwidth above 10 GHz are simultaneously generated using just one laser diode. • A parallel physical random number generator (Ph-RNG) with a bit rate of 1.04 Tbps/channel is realized. We propose and experimentally demonstrate a parallel physical random number generator (Ph-RNG) based on a single quarter-wavelength-shifted distributed feedback laser (QWS-DFB LD). Though simply connecting the two output ports of the QWS-DFB LD to form a cross-coupled perturbation, we simultaneously produce two paths of complex optical chaotic signals with a bandwidth above 10 GHz. Furthermore, a dual-channel Ph-RNG with a bit rate of order terabit per second (Tbps) is implemented by combining a multi-bit extraction method. Final results show that our generated physical random numbers can successfully pass standard benchmark tests for randomness. [ABSTRACT FROM AUTHOR]

In this paper, a strain sensing system based on Distributed-Feedback (DFB) laser array and a high effective demodulate algorithm is proposed. The uniqueness and innovation of the algorithm is in the following two aspects: one is that accurate demodulation can be achieved by scanning only 0.4 nm bandwidth of fiber Bragg grating (FBG) spectrum instead of relying on scanning FBG’s principal power peak; and the other is that the scanned spectrum can be any part of reflected spectrum of FBG sensor, which make it possible of using wavelength-division multiplexing (WDM) for FBG sensing network. In the experiment, DFB laser array with single-channel and four-channel are used to demonstrate the proposed algorithm. Experiments results show that the single-channel’s error is below 5 pm, four-channel’s is below 2 pm, strain and algorithm results show good linearity. [ABSTRACT FROM AUTHOR]

Terrestrial oils and rock extracts from the Nanpu Sag (Huanghua Depression, Bohai Bay Basin, China) were characterized by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography mass spectrometry (GC-MS). Molecular composition of neutral nitrogen and acidic oxygen compounds, mainly by N 1 , O 1 , and O 2 species were investigated in the samples. Increases in relative abundance and molecular condensation degree of oxygen-containing compounds and a decrease in the carbon number range of N 1 species were observed with the changes of kerogen from Type I to III for both the source rock extracts and the relevant oils, which indicates the influence of source input and discrimination potential. We also observed an apparent increase in the condensation degree and a decrease in the carbon number of the N 1 , O 1 and N 1 O 1 species with increasing maturity. The carbon numbers and double bond equivalent (DBE) values of the N 1 and N 1 O 1 species in the extracts showed a positive relationship (an approximately linear distribution) during thermal evolution. These results indicate that thermal maturity has a crucial influence on the composition. The relative abundance ratios of N 1 and O 1 species with specific DBE values and carbon number ranges, C 16–20 /C 21–50 -DBE 12 -N 1 , C 20–24 /C 25–50 -DBE 15 -N 1 , C 11–15 /C 16–27 -DBE 4 -O 1 , DBE 12 /DBE 9 -N 1 , and DBE 8–9 /DBE 4 -O 1 are proposed as thermal maturity indicators for the evaluation of mature and post-mature source materials. A strong primary migration fractionation effect on the heteroatom compounds was also observed, implying that these compounds can be used as migration auxiliary proxies. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the clinical results after deep anterior lamellar keratoplasty (DALK) assisted by the femtosecond laser with big-bubble technique for keratoconus.Methods: A case series of 22 eyes in 19 patients with keratoconus was enrolled in the study. The 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) was used to create a vertical side cut on donor and recipient corneas. Intraoperative and postoperative complications, uncorrected visual acuity, best-corrected visual acuity, corneal curvature, and central corneal thickness were evaluated in all patients.Results: Big-bubble and naked Descemet's membrane (DM) were successfully achieved in twenty eyes (90.9%). Intraoperative macroperforation of DM occurred in two cases and converted to full-thickness keratoplasty. The mean follow-up time was 18.8 ± 5.3 months. The best-corrected visual acuity was increased from 0.3 to 1.0, mean corneal curvature was 43.0 ± 2.3D, and mean central corneal thickness was 508.9 ± 60.1 μm (range, from 430 to 600 μm) postoperatively.Conclusion: Our results indicate that femtosecond laser-assisted DALK with big-bubble technique is an accurate, safe, and effective method to treat the patients with keratoconus. [ABSTRACT FROM AUTHOR]

Background: This study evaluated the visual function after implantation of a multifocal toric intraocular lenses (IOLs).Materials and Methods: This study involved 10 eyes from eight cataract patients with corneal astigmatism of 1.0 diopter (D) or higher who had received phacoemulsification with implantation of an AcrySof IQ ReSTOR Toric IOL. Six-month evaluations included visual acuity, spherical equivalent (SE), defocus curve, residual astigmatism, IOL rotation, contrast sensitivity (CS), wavefront aberrations, modulation transfer function (MTF), and patient satisfaction assessments.Results: At 6 months postoperatively, uncorrected distance visual acuity (logarithm of the minimum angle of resolution) was 0.09 ± 0.04, corrected distance visual acuity was 0.02 ± 0.11, and uncorrected near visual acuity was 0.12 ± 0.07. The mean SE was -0.095 ± 0.394 D (±0.50 D in 90%). Refractive astigmatism at the 6-month follow-up visit was significantly reduced to 0.35 ± 0.32 D from 1.50 ± 0.41 D presurgery (P < 0.05). The mean IOL axis rotation was 3.20 ± 1.55°. Postoperative CS levels were high. Postoperative total order aberrations (TOAs), lower-order aberrations (LOAs), higher-order aberrations (HOAs), and spherical aberrations were decreased compared with preoperative values (P < 0.05). At 3 months postoperatively, TOAs, LOAs, and HOAs with a 3 mm pupil diameter as well as TOAs, LOAs, and astigmatism aberrations with a 5 mm pupil diameter were statistically lower than those at 1-month post surgery, but without subsequent significant changes (P > 0.05). There was an increase in MTF results between preoperative and postoperative evaluations at all spatial frequencies.Conclusions: The diffractive multifocal toric IOL is able to provide a predictable astigmatic correction with apparently outstanding levels of optical quality after implantation. [ABSTRACT FROM AUTHOR]

The tunable distributed feedback (DFB) semiconductor lasers with cascaded configuration were designed and fabricated using equivalent phase shift (EPS) technique. 32-wavelength division multiplexing (WDM) channels with 50-GHz and 100-GHz wavelength spacing were experimentally demonstrated. In such a tunable laser, single mode operation can be ensured by introducing EPS and the wavelength tuning can be realized by cascaded sections with specific sampling periods combining with chip heating. The proposed approach has some advantages such as good single mode property, low fabrication cost and feasibility of monolithic integration. The experimental results show that the tuning range can be nearly up to 25 nm and the side mode suppression ratios (SMSRs) of most channels are above 40 dB. The proposed laser should be promising for cost-effective applications in WDM systems. [ABSTRACT FROM AUTHOR]

An equivalent corrugation pitch-modulated (ECPM) distributed feedback (DFB) semiconductor laser with two equivalently assisted phase shifts (EAPS) was theoretically studied and experimentally demonstrated. The simulated results showed that the longitudinal photon density distribution of the ECPM + EAPS DFB lasers was much more uniform than that of a sole ECPM DFB laser without EAPS, and the longitudinal spatial hole burning was therefore suppressed more effectively. The results of experiment showed that good single longitudinal mode operation was achieved, with side mode suppression ratio (SMSR) being over 35 dB, and the wavelength range was from 1,559.64 to 1,563.02 nm when the operation current was from 50 to 160 mA at the temperature of 25 °C, and the SMSR increased to 46.29 dB when the injection current was 130 mA. [ABSTRACT FROM AUTHOR]

ABSTRACT A distributed-feedback semiconductor laser array with buried heterostructure waveguide based on reconstruction equivalent chirp technique is experimentally demonstrated. The fabricated six-element laser array has channel spacing of 800 GHz and well meets the International Telecommunication Union standard, with relatively low threshold and high efficiency. Good single-longitudinal mode operation has been achieved at high injection current (120 mA) and high temperature (80°C), with side mode suppression ratios not lower than 40 dB, which is promising for the future wavelength division multiplexing systems. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1278-1281, 2015 [ABSTRACT FROM AUTHOR]

Abstract: The phase-shifted distributed feedback (DFB) semiconductor laser with linearly chirped grating based on reconstruction equivalent chirp (REC) technique is theoretically analyzed and experimentally demonstrated for the first time. The asymmetric property of the lasing spectrum is analyzed according to the normalized threshold gain, and the different spectra from each facet of the laser are compared. Due to the low cost and fabrication flexibility, REC technique provides a promising way for the future practical applications of DFB lasers with chirped gratings. [Copyright &y& Elsevier]

Passivity of carbon steel was examined in saturated Ca(OH) 2 solution with different alternating temperatures. The results showed that the Fe3+/Fe2+ and OH-/O2- ratios decreased, and donor density in the passive film increased with the amplitude of temperature alternation. Cracks were observed in the film when the sample experienced a higher amplitude of temperature change. Passive films on the samples in 20–50 °C and 20–60 °C alternating temperature solution were less stable than those of their counterparts in 40 °C and 50 °C solution, respectively. Furthermore, a model was proposed to explain the degradation of passive films under alternating temperature. • Passive film formed at 20–50 and 20–60 °C was less stable and protective than that formed at 40 and 50 °C, respectively. • Temperature change with the amplitude of 20 °C can't while 40 °C can cause cracks in the passive film on carbon steel. • Cracks caused by high-amplitude temperature change cannot be re-passivated in a short time. [ABSTRACT FROM AUTHOR]