Stepped-height ridge waveguide MQW polarization mode converter monolithically integrated with sidewall grating DFB laser

We report the first demonstration of a 1555 nm stepped-height ridge waveguide polarization mode converter monolithically integrated with a side wall grating distributed-feedback (DFB) laser using the identical epitaxial layer scheme. The device shows stable single longitudinal mode (SLM) operation with the output light converted from TE to TM polarization with an efficiency of >94% over a wide range of DFB injection currents (IDFB) from 140 mA to 190 mA. The highest TM mode purity of 98.2% was obtained at IDFB=180 mA. A particular advantage of this device is that only a single step of metalorganic vapor-phase epitaxy and two steps of III-V material dry etching are required for the whole integrated device fabrication, significantly reducing complexity and cost

Regrowth-free AlGaInAs MQW polarization controller integrated with sidewall grating DFB laser

We report an AlGaInAs multiple quantum well integrated source of polarization controlled light consisting of a polarization mode converter PMC, differential phase shifter(DPS), and a side wall grating distributed-feedback DFB laser. We demonstrate an asymmetrical stepped-height ridge waveguide PMC to realize TE to TM polarization conversion and a symmetrical straight waveguide DPS to enable polarization rotation from approximately counterclockwise circular polarization to linear polarization. Based on the identical epitaxial layer scheme, all of the PMC, DPS, and DFB laser can be integrated monolithically using only a single step of metalorganic vapor phase epitaxy and two steps of III V material dry etching. For the DFB-PMC device, a high TE to TM polarization conversion efficiency 98% over a wide range of DFB injection currents is reported at 1555 nm wavelength. For the DFB-PMC-DPS device, a 60 degree rotation of the Stokes vector was obtained on the Poincar\'e sphere with a range of bias voltage from 0 V to -4.0 V at IDFB is 170 mA.Comment: arXiv admin note: text overlap with arXiv:2210.1051

Inhibition the ubiquitination of ENaC and Na,K-ATPase with erythropoietin promotes alveolar fluid clearance in sepsis-induced acute respiratory distress syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) causes significant fatalities worldwide and lacks pharmacological intervention. Alveolar fluid clearance (AFC) plays a pivotal role in the remission of ARDS and is markedly impaired in the pathogenesis of ARDS. Here, we demonstrated that erythropoietin could effectively ameliorate lung injury manifestations and lethality, restore lung function and promote AFC in a rat model of lipopolysaccharide (LPS)-induced ARDS. Moreover, it was proven that EPO-induced restoration of AFC occurs through triggering the total protein expression of ENaC and Na,K-ATPase channels, enhancing their protein abundance in the membrane, and suppressing their ubiquitination for degeneration. Mechanistically, the data indicated the possible involvement of EPOR/JAK2/STAT3/SGK1/Nedd4–2 signaling in this process, and the pharmacological inhibition of the pathway markedly eliminated the stimulating effects of EPO on ENaC and Na,K-ATPase, and subsequently reversed the augmentation of AFC by EPO. Consistently, in vitro studies of alveolar epithelial cells paralleled with that EPO upregulated the expression of ENaC and Na,K-ATPase, and patch-clamp studies further demonstrated that EPO substantially strengthened sodium ion currents. Collectively, EPO could effectively promote AFC by improving ENaC and Na,K-ATPase protein expression and abundance in the membrane, dependent on inhibition of ENaC and Na,K-ATPase ubiquitination, and resulting in diminishing LPS-associated lung injuries

Design of 2 μm Wavelength Polarization Mode Controllers

A single-slot waveguide for transverse electric (TE) to transverse magnetic (TM) mode conversion operating at wavelengths around 2 μm is proposed based on an InGaSb/AlGaAsSb quantum well structure. The polarization mode convertor has a deep-etched ridge waveguide and a single shallow-etched slot, and can be fabricated in a single stage of dry-etching. The dependence of polarization conversion efficiency on slot width, slot position, slot depth and waveguide length was investigated, and a design that was insensitive to fabrication tolerances was identified. A TE-TM mode conversion efficiency of more than 97% can be obtained in a 2141-μm-long waveguide

Thick film hydrogen silsesquioxane planarization for passive component technology associated with electronic-photonic integrated circuits

Migrating electronic-photonic integrated circuits (EPICs) to higher data rates requires efficient electrical interfaces. This can be achieved with microwave technologies such as coplanar and microstrip transmission lines, but these can be difficult to apply in EPICs because of the complexity of the fabrication processes associated with monolithic integration. In this work, the authors report a novel method for planarizing a thick, low-κ film based on multiple-spins of layers of hydrogen silsesquioxane without a need for thermal curing. Films of total thicknesses of 5 and 6μm were planarized on a heavily doped InP substrate and used to realize coplanar waveguide transmission lines. The film shape is defined as an integral part of the fabrication process without any need for etching. A coplanar waveguide with a characteristic impedance of between 48 and 56Ω over the frequency range 10 MHz–67 GHz was demonstrated

Competition of electronic correlation and reconstruction in La1-xSrxTiO3/SrTiO3 heterostructures

Electronic correlation and reconstruction are two important factors that play a critical role in shaping the magnetic and electronic properties of correlated low-dimensional systems. Here, we report a competition between the electronic correlation and structural reconstruction in La1-xSrxTiO3/SrTiO3 heterostructures by modulating material polarity and interfacial strain, respectively. The heterostructures exhibit a critical thickness (tc) at which a metal-to-insulator transition (MIT) abruptly occurs at certain thickness, accompanied by the coexistence of two- and three-dimensional (2D and 3D) carriers. Intriguingly, the tc exhibits a V-shaped dependence on the doping concentration of Sr, with the smallest tc value at x = 0.5. We attribute this V-shaped dependence to the competition between the electronic reconstruction (modulated by the polarity) and the electronic correlation (modulated by strain), which are borne out by the experimental results, including strain-dependent electronic properties and the evolution of 2D and 3D carriers. Our findings underscore the significance of the interplay between electronic reconstruction and correlation in the realization and utilization of emergent electronic functionalities in low-dimensional correlated systems

Protectin conjugates in tissue regeneration 1 alleviates sepsis-induced acute lung injury by inhibiting ferroptosis

Background: Acute lung injury (ALI) is a common and serious complication of sepsis with high mortality. Ferroptosis, categorized as programmed cell death, contributes to the development of lung injury. Protectin conjugates in tissue regeneration 1 (PCTR1) is an endogenous lipid mediator that exerts protective effects against multiorgan injury. However, the role of PCTR1 in the ferroptosis of sepsis-related ALI remains unknown. Methods: A pulmonary epithelial cell line and a mouse model of ALI stimulated with lipopolysaccharide (LPS) were established in vitro and in vivo. Ferroptosis biomarkers, including ferrous (Fe2+), glutathione (GSH), malondialdehyde (MDA) and 4-Hydroxynonenal (4-HNE), were assessed by relevant assay kits. Glutathione peroxidase 4 (GPX4) and prostaglandin-endoperoxide synthase 2 (PTGS2) protein levels were determined by western blotting. Lipid peroxides were examined by fluorescence microscopy and flow cytometry. Cell viability was determined by a CCK-8 assay kit. The ultrastructure of mitochondria was observed with transmission electron microscopy. Morphology and inflammatory cytokine levels predicted the severity of lung injury. Afterward, related inhibitors were used to explore the potential mechanism by which PCTR1 regulates ferroptosis. Results: PCTR1 treatment protected mice from LPS-induced lung injury, which was consistent with the effect of the ferroptosis inhibitor ferrostatin-1. PCTR1 treatment decreased Fe2+, PTGS2 and lipid reactive oxygen species (ROS) contents, increased GSH and GPX4 levels and ameliorated mitochondrial ultrastructural injury. Administration of LPS or the ferroptosis agonist RSL3 resulted in reduced cell viability, which was rescued by PCTR1. Mechanistically, inhibition of the PCTR1 receptor lipoxin A4 (ALX), protein kinase A (PKA) and transcription factor cAMP-response element binding protein (CREB) partly decreased PCTR1 upregulated GPX4 expression and a CREB inhibitor blocked the effects ofPCTR1 on ferroptosis inhibition and lung protection. Conclusion: This study suggests that PCTR1 suppresses LPS-induced ferroptosis via the ALX/PKA/CREB signaling pathway, which may offer promising therapeutic prospects in sepsis-related ALI

Scattering Field Enhanced Biosensing Based on Sub-wavelength Split-ring Plasmonic Cavity With High Q-factor

Plasmonic structures are widely used in modern biosensor design. various plasmonic resonant cavities could efficiently achieve a high Q-factor, improving the local field intensity to enhance photoluminescence or SERS (Surface-Enhanced Raman Scattering) of small molecules. Also, the combination between virus-like particles and plasmonic structures could significantly influence the scattering spectrum and field, which is utilized as a method for biological particle detection. In this paper, we designed one kind of gold plasmonic cavity with the shape of a split-ring. An edge gap and a bonus center bulge are introduced in the split-ring structure. Our simulation is based on Finite Difference Time Domain (FDTD) method. Polarization Indirect Microscopic Imaging (PIMI) technique is used here to detect far-field mode distribution under the resonant wavelength. The simulation results demonstrate resonant peaks in the visible spectrum at about 600 nm with a Q-factor reaches to 74. Localized hot spots are generated by an edge dipole mode and a cavity hexapole mode at resonant wavelength, which is according to dark points in the PIMI sinδ image. Also, the split-ring cavity shows a sensitivity when combined with biological particles. The scattering distribution is evidently changed as a result of energy exchange between particles and split-ring cavity, indicating a promising possibility for biosensing

1.55-µm sidewall grating DFB lasers integrated with a waveguide crossing for an optical beam forming network

By using asymmetric twin-waveguide technology, a 1.55-μm sidewall grating distributed feedback laser monolithically integrated with a passive waveguide crossing was for the first time demonstrated for an optical beam forming network, which needs only one metalorganic vapor-phase epitaxy step. The distributed feedback laser with uncoated facets presents a side-mode suppression ratio of >44 dB and a low 3-dB linewidth of 68 kHz. An elliptical parabolic taper waveguide crossing had a theoretical crosstalk suppression ratio of 40 dB, while the measured cross-talk suppression ratio was at least 20 dB

Magnetic anisotropy reversal driven by structural symmetry-breaking in monolayer {\alpha}-RuCl3

Layered {\alpha}-RuCl3 is a promising material to potentially realize the long-sought Kitaev quantum spin liquid with fractionalized excitations. While evidence of this exotic state has been reported under a modest in-plane magnetic field, such behavior is largely inconsistent with theoretical expectations of Kitaev phases emerging only in out-of-plane fields. These predicted field-induced states have been mostly out of reach due to the strong easy-plane anisotropy of bulk crystals, however. We use a combination of tunneling spectroscopy, magnetotransport, electron diffraction, and ab initio calculations to study the layer-dependent magnons, anisotropy, structure, and exchange coupling in atomically thin samples. Due to structural distortions, the sign of the average off-diagonal exchange changes in monolayer {\alpha}-RuCl3, leading to a reversal of magnetic anisotropy to easy-axis. Our work provides a new avenue to tune the magnetic interactions in {\alpha}-RuCl3 and allows theoretically predicted quantum spin liquid phases for out-of-plane fields to be more experimentally accessible