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Baicalin (BA) is a flavonoid extracted from the dried root of Scutellaria baicalensisGeorgi with excellent antioxidant and anti-inflammatory biological activities. In this study, Eudragit S100 was used as the colonic target material to prepare BA colonic targeting granules (EBCGs) based on plasticizer dry powder coating technology to improve the targeting transportation performance of BA. In vitrostudies showed that EBCGs with pH-sensitive properties were successfully prepared by plasticizer dry powder coating, and in vivoanimal imaging studies showed that EBCGs could deliver BA to the colon and inhibit the release of BA in the upper gastrointestinal tract (GIT). In vivostudies showed that EBCGs had good therapeutic effects in colitis, which reduced expression levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) and increased superoxide dismutase (SOD) activities in the colonic tissues of rats with colitis. In conclusion, Eudragit S100 could be used for the preparation of multi-unit oral colon-targeted formulations by plasticizer dry powder coating technology, and our prepared EBCGs had good colon-targeting properties, which could improve the therapeutic effect and provide a potential application for ulcerative colitis (UC).

Toward the application of 400 G optical receiver chips in optical communication systems, this paper presents a $1\times 4$ photodetector (PD) array with a monolithic integrated InP microlenses structure. The absorption layer of the PD array in question includes the non-depleted, partially depleted, and depleted regions. This third-order composite absorber layer accelerates the diffusion of electrons in the absorber layer and balances the transport times of holes and electrons. Therefore, the high-speed and high responsivity characteristics of the device can be realized. The integration of InP microlenses on the backside of the PD allows the effective photosensitive surface area to be increased and the incident light alignment deviation to be compensated. Tests yielded a 3-dB bandwidth of the PD array at 1310 nm greater than 40 GHz, with a peak responsivity of 0.64 A/W. The responsivity of two types of PDs was measured when incident at a distance of $10~\mu \text{m}$ away from the main optical axis. The responsivity of the integrated microlenses decreased to 67.05% of the maximum value. Compared to the device without integrated microlenses, the responsivity increased by 66.76%.

A high-speed and high-power modified uni-traveling-carrier photodiode (MUTC-PD) is optimized and fabricated. The optimization method takes carrier transport as the core and considers the hole transport time limited bandwidth of the MUTC-PD for the first time. Taking into account the impact of the electron transport time and RC time constant on device performance, the device is simulated and fabricated. In structure epitaxy, it is proposed to use graded doping to fit Gaussian doping to reduce the epitaxial growth error. The measured bandwidth of the MUTC-PD reaches 34 GHz and the RF output power reaches 17.1 dBm with the mesa diameter of $20~\mu \text{m}$ . In addition, the influence of modulation depth on high-speed and high-power performance is studied.

In this letter, we propose a broadband achromatic metalens that exhibits high focusing efficiency within the wavelength range of 1270–2070 nm and is insensitive to polarization. Within the operating wavelength range, the metalens displays a focal length shift of only $\pm 0.5~\mu \text{m}$ and exhibits excellent achromatic properties. The average focusing efficiency of the metalens is 56%, with a maximum focusing efficiency of 70.7%. Compare with no metalens, the metalens can enhance the transmissivity of incident light by approximately 10%. And the average full width at half maximum (FWHM) of this structure is $0.5526~\mu \text{m}$ . In the design process, we propose a new algorithm. The concept behind this method has significant implications for other inverse design algorithms.

A cascade array structure and depleted layer thickness design method of uni-traveling-carrier photodetector (UTC-PD) for terahertz applications is proposed. The cascade array structure can increase the 3dB bandwidth from 203 GHz to 255 GHz compared to the high-speed single UTC-PD with a diameter of $3 ~\mu \text{m}$ by effectively reducing the overall device capacitance. The 3dB bandwidth can be further improved to 267 GHz by thickness optimization. The combination of cascade array structure and depleted layer thickness optimization can significantly improve the saturation output power of the device at 100, 200 and 300 GHz, which enables the design of cascade UTC-PD array to be applied in terahertz (THz) band.

We report the measurements and characterizations of optoelectronic harmonic mixing in a modified uni-traveling carrier photodetector (MUTC-PD). A systematic study of the bias voltage-dependent properties of the output power under different input optical power levels has been made and the proper operating conditions for different mixing modes have been investigated. In addition to the fundamental mixing, the higher-order harmonic mixing and RF subharmonic mixing products were obtained. The harmonic mixing mechanism is mainly attributed to the nonlinearity of the dependence of the output power on the bias voltage. Flat intermediate responses over a wide RF signal frequency range were measured for the fundamental mixing and the high-order RF subharmonic mixing. The feasible harmonic optoelectronic mixing in MUTC-PD shows great application potential in the wireless multichannel communication system.

Recently, numerous wearable devices for gesture recognition have been reported; however, most of them are fabricated by assembling the separately designed sensing layers with the substrate through linking agents, which will lead to the shifting or detaching of the sensing layers after long-duration use. Subsequently, over-reliance on multiple filtering algorithms to smooth the collected datasets becomes very popular, unavoidably resulting in the loss of data features and overfitting. In our point of view, it is much more crucial and effective for gesture recognition performance to reinforce the stability of the sensing layers. Therefore, in this work, we designed a type of integrated MXene/polyurethane (I-M/PU) sensor based on textile fabrics and further prepared a data glove, a smart wristband, and a smart elbow pad. A wearable system for gesture recognition with ultrahigh sensitivity to strain, as well as excellent stability and durability, is successfully realized by the synergy of those three devices. The collected original data by the integrated sensors were steady with specific features, making the simplification of the classification model feasible. Finally, 19 static gestures (including nine complex gestures) with a recognition accuracy of 100% in 6998 data samples have been impressively achieved by the simple multilayer perceptron (MLP) algorithm, which is the state-of-art best result as we know in the gesture recognition reports without any assistant computer vision algorithms, demonstrating our solution with a promising prospect in virtual reality (VR) and human–machine interaction (HMI) fields.

An interval-sweeping pulse equivalent sampling (ISPES) method based on compressed sensing technique is proposed to enhance the frequency response of phase-sensitive optical time-domain reflectometry (Φ-OTDR). The proposed method achieves an equivalent high-sampling-rate acquisition of Rayleigh backscattered signals along each sensing point of the fiber by the interval-sweeping pulse sampling and compressed sensing reconstruction. Meanwhile, based on the Whittaker-Shannon interpolation formula, the observation matrix corresponding to the interval-sweeping pulse sampling is successfully constructed and proved, which is easy to implement in hardware. In experiments, an ultrasonic signal with a frequency up to 28 kHz at the end of a 4.4-km sensing fiber is accurately identified by using this method, which outperforms other compressed-sensing-based methods. And multi-frequency vibration signals are also accurately detected. Besides, this method performs signal compression while sampling. The number of samples is only 13.3% of the reconstructed data, significantly reducing the amount of data acquisition/transmission/storage. Therefore, the proposed method can effectively enhance the frequency response of Φ-OTDR to sparse-wideband vibration signals without any hardware modification. It also has great advantages in reducing the hardware burden and improving the response speed.

In this paper, we propose a high-speed PIN photodiode with a composite absorption layer. It supports a 3-dB bandwidth of 43 GHz and can be used in 100 Gbit/s optical receivers. The composite absorption layer consists of a gradually-doped p-type absorption layer and an undoped absorption layer. It has different carrier transport mechanisms from the traditional PIN-PD with a single intrinsic absorption layer. The gradually-doped p-type absorption layer accelerates electron diffusion in the p-type absorption layer. Comparison of three kinds of PIN photodiodes with different absorption layers shows that the proposed PIN-PD provides the highest bandwidth while ensuring satisfactory responsivity. The simulation used a numerical model, calculated by Crosslight APSYS software. The results were compared with the analytical method and obtained a good agreement. This work offers a novel structure and good guidance for the design and optimization of photodiodes.

In this Letter, a novel “stepped particle swarm optimization” (SPSO) based on field intensity adjustment is proposed. After that, we used this algorithm to design a sub-wavelength converging grating that could be integrated with the detector on the back. Firstly, the advantages of reverse design in the process of two-dimensional or multi-element grating pattern design were summarized by comparing the theory of forward and reverse design. Then, the common “particle swarm optimization” (PSO) and our proposal were compared in the reverse design process; we found that the field strength at the focal point obtained by the improved algorithm was approximately twice of the conventional PSO, and the SPSO had higher computational efficiency and better global convergence. The value of the SPSO had been steadily enlarged, which significantly improved the performance of the sub-wavelength convergent grating. Finally, the property of the sub-wavelength converging grating was simulated, and we found that the grating could achieve good convergence in the focal length range of 100–150 µm, and had a strong ability to compensate for the position deviation of the incident light. In actual optical communications, this sub-wavelength converging grating will play an important role in alleviating the bandwidth and quantum efficiency, improving the performance of the detectors.

Since the first novel gene discovery for a Mendelian condition was made via exome sequencing (ES), the rapid increase in the number of genes known to underlie Mendelian conditions coupled with the adoption of exome (and more recently, genome) sequencing by diagnostic testing labs has changed the landscape of genomic testing for rare disease. Specifically, many individuals suspected to have a Mendelian condition are now routinely offered clinical ES. This commonly results in a precise genetic diagnosis but frequently overlooks the identification of novel candidate genes. Such candidates are also less likely to be identified in the absence of large-scale gene discovery research programs. Accordingly, clinical laboratories have both the opportunity, and some might argue a responsibility, to contribute to novel gene discovery which should in turn increase the diagnostic yield for many conditions. However, clinical diagnostic laboratories must necessarily balance priorities for throughput, turnaround time, cost efficiency, clinician preferences, and regulatory constraints, and often do not have the infrastructure or resources to effectively participate in either clinical translational or basic genome science research efforts. For these and other reasons, many laboratories have historically refrained from broadly sharing potentially pathogenic variants in novel genes via networks like Matchmaker Exchange, much less reporting such results to ordering providers. Efforts to report such results are further complicated by a lack of guidelines for clinical reporting and interpretation of variants in novel candidate genes. Nevertheless, there are myriad benefits for many stakeholders, including patients/families, clinicians, researchers, if clinical laboratories systematically and routinely identify, share, and report novel candidate genes. To facilitate this change in practice, we developed criteria for triaging, sharing, and reporting novel candidate genes that are most likely to be promptly validated as underlying a Mendelian condition and translated to use in clinical settings.

Formation mechanism and optical properties of InAs quantum dots (QDs) on the surface of GaAs nanowires (NWs) were investigated. This NW-QDs hybrid structure was fabricated by Au-catalyzed metal organic chemical vapor deposition. We found that the formation and distribution of QDs were strongly influenced by the deposition time of InAs as well as the diameter of GaAs NWs. A model based on the adatom diffusion mechanism was proposed to describe the evolution process of the QDs. Photoluminescence emission from the InAs QDs with a peak wavelength of 940 nm was observed at room temperature. The structure also exhibits a decoupling feature that QDs act as gain medium, while NW acts as Fabry–Perot cavity. This hybrid structure could serve as an important element in high-performance NW-based optoelectronic devices, such as near-infrared lasers, optical detectors, and solar cells.

3D assembly technology is a cutting-edge methodology for constructing high-performance and multifunctional photodetectors since some attractive photodetection features such as light trapping effect, omnidirectional ability, and high spatial resolution can be introduced. However, there has not been any report of 3D-assembled multimode photodetectors owing to the lack of design and fabrication guideline of electrodes serving for 3D heterostructures. In this study, a 3D-assembled dual-mode photodetector (3DdmPD) was realized successfully via the clever electrical contact between the rolled-up tubular graphene/GaAs/InGaAs heterostructure and planar metal electrode. Arbitrary switching of three coplanar electrodes makes the as-fabricated tubular 3D photodetector work at the unbiased photodiode mode, which is suitable for energy conservation high-speed photodetection, or the biased photoconductive mode, which favors extremely weak light photodetection, fully showing the advantages of multifunctional detection. In more detail, the Ilight/Idarkratio reached as high as 2 × 104, and a responsivity of 42.3 mA/W, a detectivity of 1.5 × 1010Jones, as well as a rising/falling time (τr/τf) of 360/370 μs were achieved under the self-driven photodiode mode. Excitingly, 3DdmPD shows omnidirectional photodetection ability at the same time. When 3DdmPD works at the photoconductive mode with 5 V bias, its responsivity is extremely high as 7.9 × 104A/W and corresponding detectivity is increased to 1.0 × 1011Jones. Benefiting from the totally independent coplanar electrodes, 3DdmPD is much more easily integrated as arrays that are expected to offer the function of high-speed omnidirectional image-sensing with ultralow power consumption than the planar counterparts which share communal bottom electrodes. We believe that our work can contribute to the progress of 3D-assembled optoelectronic devices.

As an emerging ultrathin semiconductor material, Bi2O2Se exhibits prominent performances in electronics, optoelectronics, ultrafast optics, etc.However, until now, the in-plane growth of Bi2O2Se thin films is mostly fulfilled on atomically flat mica substrates with interfacial electrostatic forces setting obstacles for Bi2O2Se transfer to fabricate functional van der Waals heterostructures. In this work, controlled growth of inclined Bi2O2Se ultrathin films is realized with apparently reduced interfacial contact areas upon mica flakes. Consequently, the transfer of Bi2O2Se could be facile by overcoming weaker electrostatic interactions. From cross-sectional characterizations at the Bi2O2Se/mica interfaces, it is found that there are no oxide buffer layers in existence for both in-plane and inclined growths, while the un-neutralized charge density is apparently decreased for inclined films. By mechanical pressing, inclined Bi2O2Se could be transferred onto SiO2/Si substrates, and back-gated Bi2O2Se field effect transistors are fabricated, outperforming previously reported in-plane Bi2O2Se devices transferred with the assistance of corrosive acids and adhesive polymers. Furthermore, Bi2O2Se/graphene heterostructures are fulfilled by a probe tip to fabricate hybrid phototransistors with pristine interfaces, exhibiting highly efficient photoresponses. The results in this work demonstrate the potential of inclined Bi2O2Se to act as a building block for prospective van der Waals heterostructures.

The RecQ DNA helicase WRN is a synthetic lethal target for cancer cells with microsatellite instability (MSI), a form of genetic hypermutability that arises from impaired mismatch repair1–4. Depletion of WRN induces widespread DNA double-strand breaks in MSI cells, leading to cell cycle arrest and/or apoptosis. However, the mechanism by which WRN protects MSI-associated cancers from double-strand breaks remains unclear. Here we show that TA-dinucleotide repeats are highly unstable in MSI cells and undergo large-scale expansions, distinct from previously described insertion or deletion mutations of a few nucleotides5. Expanded TA repeats form non-B DNA secondary structures that stall replication forks, activate the ATR checkpoint kinase, and require unwinding by the WRN helicase. In the absence of WRN, the expanded TA-dinucleotide repeats are susceptible to cleavage by the MUS81 nuclease, leading to massive chromosome shattering. These findings identify a distinct biomarker that underlies the synthetic lethal dependence on WRN, and support the development of therapeutic agents that target WRN for MSI-associated cancers.

Structural variants (SVs) rearrange large segments of DNA1and can have profound consequences in evolution and human disease2,3. As national biobanks, disease-association studies, and clinical genetic testing have grown increasingly reliant on genome sequencing, population references such as the Genome Aggregation Database (gnomAD)4have become integral in the interpretation of single-nucleotide variants (SNVs)5. However, there are no reference maps of SVs from high-coverage genome sequencing comparable to those for SNVs. Here we present a reference of sequence-resolved SVs constructed from 14,891 genomes across diverse global populations (54% non-European) in gnomAD. We discovered a rich and complex landscape of 433,371 SVs, from which we estimate that SVs are responsible for 25–29% of all rare protein-truncating events per genome. We found strong correlations between natural selection against damaging SNVs and rare SVs that disrupt or duplicate protein-coding sequence, which suggests that genes that are highly intolerant to loss-of-function are also sensitive to increased dosage6. We also uncovered modest selection against noncoding SVs in cis-regulatory elements, although selection against protein-truncating SVs was stronger than all noncoding effects. Finally, we identified very large (over one megabase), rare SVs in 3.9% of samples, and estimate that 0.13% of individuals may carry an SV that meets the existing criteria for clinically important incidental findings7. This SV resource is freely distributed via the gnomAD browser8and will have broad utility in population genetics, disease-association studies, and diagnostic screening.

Vaccination offers protection against infectious diseases, yet pre-existing criteria that predict vaccine efficacy or adverse events remain unknown. Hayday and colleagues identify cellular and molecular signatures in humans immunized with adjuvanted swine flu vaccine.

We present a concise approach to design focusing reflectors using concentric circular subwavelength high-contrast gratings (CCSW-HCGs). With this method, we design a high-numerical-aperture, high-reflectivity CCSW-HCG focusing reflector. By designing the CCSW-HCG structure, the grating can give the target phase front of reflected light while maintaining a high reflectivity. The properties of focusing and reflection are numerically studied with the finite element method. Simulation results show that, when the incident wavelength is 1550 nm, the reflectivity is 0.8538, and the numerical aperture is up to 0.9213. At the reflection focal plane, the full width at half-maximum of the field distribution is 0.9845 μm. Furthermore, the CCSW-HCG can simultaneously focus the reflected and transmitted light and has a strong robustness.

A reflection-enhanced dual-absorption InP-PIN/GaAs-DBR photodetector was fabricated and characterized. The photodetector is monolithically integrated using a heteroepitaxy growth of an InGaAs/InP dual-absorption “PINIP” structure on the GaAs/AlGaAs Bragg reflectors. These features lead to an increase in quantum efficiency over a wide wavelength range while maintaining a high speed. The measured quantum efficiency was increased by 48.8% in comparison with that without reflectors. A quantum efficiency of 64% at a wavelength of 1522 nm and a 3 dB bandwidth of 26 GHz at a reverse bias of 3 V were simultaneously obtained in the device.

We designed a tunable wavelength-selective quasi-resonant cavity enhanced photodetector (QRCE-PD) based on a high-contrast subwavelength grating (SWG). According to simulation results, its peak quantum efficiency is 93.2%, the 3 dB bandwidth is 33.5 GHz, the spectral linewidth is 0.12 nm, and the wavelength-tuning range is 28 nm (1536–1564 nm). The QRCE-PD contains a tunable Fabry–Perot (F-P) filtering cavity (FPC), a symmetrical SWG deflection reflector (SSWG-DR), and a built-in p-i-n photodiode. The FPC and the SSWG-DR form an equivalent multi-region F-P cavity together by multiple mutual mirroring, which makes the QRCE-PD a multi-region resonant cavity enhanced photodetector. But, QRCE-PD relies on the multiple-pass absorption enhanced effect to achieve high quantum efficiency, rather than the resonant cavity enhanced effect. This new photodetector structure is significant for the application in the dense wavelength division multiplexing systems.

Linearity is a very important parameter to measure the performance of avalanche photodiodes (APDs) under high input optical power. In this paper, the influence of the absorption layer on the linearity of APDs is carefully studied by using bandgap engineering with the structure model of separated absorption, grading, charge, multiplication, charge, and transit (SAGCMCT). The simulated results show that in the hybrid absorption layer device structure the 1 dB compression point can be improved from −9 dBm to −2.1 dBm by increasing the proportion of the p-type absorption layer. In the device structure with only one absorption layer, increasing the doping level of the absorption layer can also improve the 1 dB compression point from −8.6 dBm to 1.43 dBm at a gain of 10. Therefore, the absorption layer is very critical for the linearity of APDs.

Mendelian disease genomic research has undergone a massive transformation over the past decade. With increasing availability of exome and genome sequencing, the role of Mendelian research has expanded beyond data collection, sequencing, and analysis to worldwide data sharing and collaboration.

In this paper, we study non-Gaussianity generated by a single scalar field in slow-roll inflation in the framework of the nonrelativistic general covariant Hořava-Lifshitz theory of gravity with the project-ability condition and an arbitrary coupling constant λ, where λ characterizes the deviation of the theory from general relativity (GR) in the infrared. We find that the leading effect of self-interaction, contrary to the case of the minimal scenario of GR, is in general of the order ân ε3/2, where ε is a slow-roll parameter, and ân(n = 3, 5) are the dimensionless coupling coefficients of the sixth-order operators of the Lifshitz scalar and have no contributions to power spectra and indices of both scalar and tensor. The bispectrum, comparing with the standard one given in GR, is enhanced and gives rise to a large value of the nonlinearity parameter ｆNL. We study how the modified dispersion relation with high order moment terms affects the evaluation of the mode function and in turn the bispectrum, and we show explicitly that the mode function takes various asymptotic forms during different periods of its evolution. In particular, we find that it is in general of superpositions of oscillatory functions, instead of plane waves like in the minimal scenario of GR. This results in a large enhancement of the folded shape in the bispectrum. [ABSTRACT FROM AUTHOR]

A subwavelength plasmonic waveguide composed of a pair of comb-shape nanorod chains is proposed. The electromagnetic energy can be transported in the waveguide via the interaction strength of magnetoinductive coupling as well as conduction current exchange. Finite Element Method simulation results reveal that for such a waveguide composed of 50 pairs of 400 nm-long-nanorods, a passband ranging from zero to cutoff frequency 156.2 THz, and an effective propagation length of 20.87 μm can be achieved simultaneously. The proposed mechanism of energy transport in the nanoscale has potential applications in subwavelength transmission lines for a wide range of integrated optical devices.

Hybrid integrated photodetectors with flat-top steep-edge spectral responses that consist of an Si-based multicavity Fabry–Perot (F–P) filter and an InP-based p-i-n absorption structure (with a 0.2 μm In_0.53Ga_0.47As absorption layer), have been designed and fabricated. The performance of the hybrid integrated photodetectors is theoretically investigated by including key factors such as the thickness of each cavity, the pairs of each reflecting mirror, and the thickness of the benzocyclobutene bonding layer. The device is fabricated by bonding an Si-based multicavity F–P filter with an InP-based p-i-n absorption structure. A hybrid integrated photodetector with a peak quantum efficiency of 55% around 1549.2 nm, the −0.5  dB band of 0.43 nm, the 25 dB band of 1.06 nm, and 3 dB bandwidth more than 16 GHz, is simultaneously obtained. Based on multicavity F–P structure, this device has good flat-top steep-edge spectral response.

Based on the generalized stochastic nonlinear Schrödinger equation, the effect of intrapulse Raman scattering (IRS) on broadband amplitude noise of supercontinuum (SC) generated in the normal dispersion regime is investigated numerically. The results show that, in the normal dispersion regime, where the IRS contributes less to the bandwidth of the SC spectrum, the broadband amplitude noise of SC is amplified significantly in the process of SC generation because of the existence of IRS effect. Using fiber with an optimal negative dispersion slope, the IRS effect can be suppressed, and thus the SC amplitude noise is reduced without spectral bandwidth loss.

This paper presents the design and analysis of a Si-based tunable flattop photodetector realized by the introduction of a stepped Fabry–Perot cavity, which can be thermally tuned via applying tuning power on its tuning electrode. By using a transfer matrix method, the spectral response of the photodetector is simulated in detail, indicating a flattop line shape can be achieved with an optimum step height. A trade-off residing in this device between the free spectrum range and the ease of fabrication of step height is also revealed and analyzed. In the final design of the photodetector, 1 dB linewidth of 0.5 nm, 3 dB linewidth of 0.8 nm, 6 dB linewidth of 1.2 nm, peak quantum efficiency of 40%, tuning efficiency of 91 mW/nm are theoretically obtained. We discuss the epitaxial growth and fabrication of the photodetector in the end, exhibiting the mature technique available for this device.

Analysis of light field distribution within a dual-absorption RCE p-i-n photodetector has been performed. A formula for the field distribution inside the cavity is derived. This formula is derived from the continuity equations, and employed to evaluate the frequency response of the dual-absorption RCE photodetector. This photodetector has been optimized for high-speed applications. The optimized structure shows a 3dB bandwidth of 20 GB with intrinsic absorption region to be 400nm, as well as effective illumination area and peak quantum efficiency to be 900 m2and 92%, respectively.

This paper presents the design and analysis of a novel resonant cavity enhanced photodetector which is realized by utilizing concentric circular subwavelength gratings (CC-SWGs) as reflective mirrors. The CC-SWG proposed here can achieve a reflectivity of higher than 99% within a broad wavelength range from 1.37 to 1.63 m. The calculated peak quantum efficiency of the designed photodetector can achieve 90% at 1.55 m.

The effect of growth temperature on InAs QDs grown by metal-organic chemical vapor deposition (MOCVD) was investigated in detail. Growth temperature affects InAs QDs in three ways, including the reconstruction mode of new InAs crystal faces, the migration length of adatoms, band gaps of InAs QDs, and the interaction among three aspects was studied. The variation of density, size and wavelength was experimentally demonstrated. The high density of 5.2×1010cm-2was obtained. The room temperature wavelength of InAs/GaAs QDs using GaAs as capping layer reached 1240nm.

Three asymmetric multi-core fibers namely 3-linear-core-array fiber, 5-linear-core-array fiber and 5-circular-core-array fiber were designed. The supermode characteristics were investigated using a finite element method (FEM) with perfect matched layer (PML) boundaries. The profiles of supermodes supported by these multi-core fibers were presented. The dispersion characteristics of these multi-core fibers had been analyzed. The numerical results show that the peak value group velocity dispersion of the 5-circular-core-array fiber can reach -2.4×105ps/nm•km, and the GVD bandwidth is up to 25nm(1535-1560nm), covering almost the whole C-wavelength band. It can compensate for more than 13000 times its own length that of the ordinary SMF.

A dual-parallel-core fiber is proposed for dispersion compensation of single mode fibers (SMFs) by using coupled-mode theory. From the numerical results, the two-parallel-core structure exhibits very high negative chromatic dispersion [-9.7794 × 105ps/km/nm], and full width at half maximum dispersion (FWHM) of ~6nm.

The effect of the graded InxGa1-xAs layer on the distribution of the strain was studied by calculating the strain of different models using the finite element method. The results demonstrate that the graded InxGa1-xAs layer can reduce the strain and thus lead to longer emission wavelength. The results also demonstrate that the graded InxGa1-xAs layer can increase strain in the GaAs capping layer which cause disadvantage to grow stacked InAs/GaAs QD structure. But the strain can be released though increase the thickness of spacer layer when grow stacked structure.

A novel tunable resonant cavity enhanced photodetector (RCE-PD) is achieved by using an air gap. The optical properties of the photodetector are designed by using the transfer matrix method (TMM). The quantum efficiency (QE) of the tunable RCE-PD is calculated and the optimizing structure is obtained. It is revealed that the peak QE increases to the highest value ( 92%) when the thickness of active layer is 106nm. When the air layer thickness changed 20nm under a low bias voltage, the peak wavelength blue shifts from 1550nm to 1547.9nm and the QE of the device keeps almost invariant at the same time.

GaAs/InxGa1-xAs/GaAs double-heterostructure nanowires were grown by Metal-organic Chemical Vapor Deposition on GaAs (1 1 1)B substrate using the vapor-liquid-solid growth method. By tuning the In content(x) from 0.2 to 1, we fabricated several GaAs/InxGa1-xAs/GaAs nanowire heterostructrues with different InxGa1-xAs parts and studied their characteristics. We found that all the InGaAs segments were successfully grown on GaAs sections, while the InAs nanowires were grown kinked or downward. By inserting a composition-graded InxGa1-xAs buffer segment between GaAs and InAs nanowires, high yield of straight GaAs/InxGa1-xAs/GaAs nanowire heterostructrues were realized.

Vertical zinc blende GaAs/AIGaAs heterostructure nanowires were grown at different temperatures by met-alorganic chemical vapor deposition via Au-assisted vapor-liquid-solid mechanism. It was found that radial growth can be enhanced by increasing the growth temperature. The growth of radial heterostructure can be realized at temperature higher than 500°C, while the growth temperature of axial heterostructure is lower than 440°C. The room temperature photoluminescence properties of the nanowires were investigated and the relevant growth mechanism was discussed. [Copyright &y& Elsevier]

A novel scheme that employing the coherent receiver in atmospheric laser communication system was proposed in this paper. DPSK format modulation is adopted to overcome atmospheric turbulence and multipath fading. Coherent receiver is used to improve system's sensitivity. Testing bed was setup and eye diagram can be measured. Real time BER would be measured soon.

The optical transmission system is being upgraded from 10G to 40G even 100G due to the increasing demands of wide-bandwidth network. We numerically investigate the nonlinear tolerance of 112 Gb/s polarization-multiplexed return-to-zero differential quadrature phase-shift keying signal with different types of neighboring channels on a 50-GHz grid over 1,000 km field fiber. Our transmission result proves showing the feasibility of 100G overlaying existing 10G/40G commercial systems despite the presence of strong cross-phase modulation.

N-doped GaAs nanowires (NWs) were grown on GaAs (111) B substrate by means of vapor-liquid-solid (VLS) mechanism in a metalorganic chemical vapor deposition (MOCVD) system. Two flux rates of n-type dopants used for GaAs NWs growth were researched. For comparison, undoped GaAs NWs were grown at the same conditions. It is found that all NWs are vertical to the substrate and no lateral growth occurs. The growth rate is proportional the flux rates of n dopant. It is observed that there is Gibbs-Thomson effect in doped NWs. Pure zinc blende structures without any stacking faults from bottom to top for all three samples were achieved.

In this paper, analytical method is employed to analyze the system strain energy and critical diameter of one kind of longitudinally heterostructure nanowire which contains component gradient buffer sections. Based on the critical diameter model of F. Glas in heterostructure nonawires, calculation has been made to research on how does single-layer thickness and total thickness of gradient buffer effect the critical radius of the system. The results illustrate that component gradient buffer layer can effectively reduce the system strain energy, and the thinner the single-layer buffer section thickness , the more obvious the improvement of its critical radius; if the lattice mismatch of the heterostructure nonawires is smaller, the strain energy can be reduced more significantly, also the greater rate of increase of its critical radius. The freedom cut of the nonawires diameter can be realized by controlling the component and thickness of buffer sections. Using Au assistant MOVCD method, we can get high-quality nonawires with component gradient buffer sections, in contrast to the bad quality SEM image of the nonawires without buffer layers, which effectively prove the above conclusions.

A novel approach, using a PNA(network analyzer) instead of Spectrum Analyzer in optical heterodyne measurement system, to characterize the frequency response performance of photodetectors is proposed. This scheme synthesize the advantages of both the optical heterodyne technique and accurate calibration technique of PNA. In this paper, two tunable narrow linewidth lasers are used to reduce the errors caused by the variations in the linewidth of the beat signal, and the optical power is accurately monitored and controlled to minimize the noise due to laser output power fluctuates. We analyze the influence of variations linewidth, and associative simulation on this influence is been done. And an error eliminate model is presented to remove the influence of variations linewidth. SOLT calibration technique is used to accurately calibrate the power receiver of PNA. In addition, when configured with an 80 GHz frequency mixer in this measurement system, we can achieve the frequency response measurement of a 80 GHz photodetector since we are using a 40 GHz PNA.

We present a novel and robust design for a photonic crystal fiber with flattened dispersion, a highly nonlinear coefficient, and low confinement loss for its dual concentric core structure. The proposed fiber has a modest number of design parameters. Analysis results show that the proposed eight-ring photonic crystal fiber is obtained with a nonlinear coefficient greater than 33 W^−1 km^−1 and a near-zero dispersion slope of −7.828×10^−4 ps/nm^2/km at 1550 nm. Ultraflat dispersion with a value between −1.380 and +0.9860 ps/nm/km and a superlow-order confinement loss of 10^−4 dB/km are simultaneously obtained ranging from 1400 to 1625 nm. For practical fabrication, the influence of random imperfections of airhole diameters on dispersion and nonlinearity is discussed to verify the robustness of our design.

A new type of photodetector with cascaded waveguide grating filters as a bottom reflection mirror is proposed. A greatly improved spectral response is shown to follow by the integration of a waveguide grating into classical thin-film homogeneous layers. Calculation results for a single grating, a cascaded-double grating, and a cascaded-triple grating structure are demonstrated. An increasing rectangular spectral response is obtained by cascading two or three grating filters. Compared with a traditional photodetector with distributed Bragg reflectors, this new type of photodetector with the same materials requires significantly fewer layers while maintaining narrow flattop response, high peak efficiency, and low sideband reflectance.

Introduction:According to the potential heterogeneity of acute kidney injury (AKI) in critically ill patients with cardiovascular diseases, we explored the subphenotypes of AKI and evaluated the prognostic differences among AKI subphenotypes.Hypothesis:We hypothesized that patients with different AKI subphenotypes would suffer different prognosis.Methods:Clinical information from the Medical Information Mart for Intensive Care (MIMIC)-III database was enrolled. Latent class analysis (LCA) was used to explore the potential subphenotypes of AKI in critically ill patients with cardiovascular diseases. The number of classes was identified using the Bayesian information criterion and entropy. The differences in prognostic ability among the AKI subphenotypes were evaluated by logistic regression analysis.Results:In this study, a total of 7738 AKI patients were enrolled and divided into 4 heterogeneous subphenotypes by using LCA. The subphenotypes showed remarkable dofference from kidney disease classified by improving Global Outcomes (KDIGO) stages. Notedly, though both dominated by stage 2, the mortality between class 4 and class 1 classified by LCA were significantly different (15.2% vs. 1.6%, p<0.05). The trend remained the same after further adjustment, with an odds ratio of 12.31 (95% confidence interval, 8.96-16.89).Conclusions:LCA was feasible for AKI classification and different subphenotypes prognosis prediction in critically ill patients with cardiovascular disease. Our study revealed the potential heterogeneity of AKI patients, which is worthy of further investigation.

Using two-step method InP epilayers were grown on GaAs(100) substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). X-ray diffraction (XRD) and room-temperature (RT) photoluminescence (PL) were employed to characterize the quality of InP epilayer. The best scheme of growing InP/GaAs(100) heterostructures was obtained by optimizing the initial low-temperature (LT) InP growth conditions, investigating the effects of thermal cycle annealing (TCA) and strained layer superlattice (SLS) on InP epilayers. Compared with annealing, 10-period Ga0.1In0.9P/InP SLS inserted into InP epilayers can improve the quality of epilayers dramatically, by this means, for 2.6-micron-thick heteroepitaxial InP, the full-widths at half-maximum (FWHMs) of XRD 'omega' and 'omega'-2'theta' scans are 219 and 203 arcsec, respectively, the RT PL spectrum shows the band edge transition of InP, the FWHM is 42 meV. In addition, the successful growth of InP/In0.53Ga0.47As MQWs on GaAs(100) substrates indicates the quality of device demand of InP/GaAs heterostructures.