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The ability to amplify optical signals is of pivotal importance across science and technology typically using rare-earth-doped fibres or gain media based on III-V semiconductors. A different physical process to amplify optical signals is to use the Kerr nonlinearity of optical fibres through parametric interactions(1,2). Pioneering work demonstrated continuous-wave net-gain travelling-wave parametric amplification in fibres(3), enabling, for example, phase-sensitive (that is, noiseless) amplification(4), link span increase(5), signal regeneration and nonlinear phase noise mitigation(6). Despite great progress(7-15), all photonic integrated circuit-based demonstrations of net parametric gain have necessitated pulsed lasers, limiting their practical use. Until now, only bulk micromachined periodically poled lithium niobate (PPLN) waveguide chips have achieved continuous-wave gain(16,17), yet their integration with silicon-wafer-based photonic circuits has not been shown. Here we demonstrate a photonic-integrated-circuit-based travelling-wave optical parametric amplifier with net signal gain in the continuous-wave regime. Using ultralow-loss, dispersion-engineered, metre-long, Si3N4 photonic integrated circuits(18) on a silicon chip of dimensions 5 x 5 mm(2), we achieve a continuous parametric gain of 12 dB that exceeds both the on-chip optical propagation loss and fibre-chip-fibre coupling losses in the telecommunication C band. Our work demonstrates the potential of photonic-integrated-circuit-based parametric amplifiers that have lithographically controlled gain spectrum, compact footprint, resilience to optical feedback and quantum-limited performance, and can operate in the wavelength ranges from visible to mid-infrared and outside conventional rare-earth amplification bands.

Mycobacterium tuberculosis /human immunodeficiency virus (MTB/HIV) coinfection has become an urgent problem in the field of prevention and control of infectious diseases in recent years. Adoptive cellular immunotherapy using antigen-specific T-cell receptor (TCR) engineered T cells which recognize the specific antigen artificially may have tremendous potential in anti-MTB/HIV coinfection. We have previously successfully identified a MTB Ag85B 199-207 and HIV-1 Env 120-128 peptide-bispecific TCR screened out from peripheral blood mononuclear cells of a HLA-A∗0201 + healthy individual and have further studied that how residues on the predicted complementarity determining region (CDR) 3 of the β chain contribute to the bispecific TCR contact with the peptide-MHC. However, it is not clear which amino acids in the predicted CDR3α of the bispecific TCR play a crucial role in ligand recognition.The variants in the CDR3α of the bispecific TCR were generated using alanine substitution. We then evaluated the immune effects of the five variants on T-cell recognition upon encounter with the MTB or HIV-1 antigen.Mutation of two amino acids (E112A, Y115A) in CDR3α of the bispecific TCR caused a markedly diminished T-cell response to antigen, whereas mutation of the other three amino acids (S113A, P114A, S116A) resulted in completely eliminated response.This study demonstrates that Ser 113 , Pro 114 and Ser 116 in CDR3α of the bispecific TCR are especially important for antigen recognition. These results will pave the way for the future development of an improved high-affinity bispecific TCR for use in adoptive cellular immunotherapy for MTB/HIV coinfected patients.

Metal halide perovskite ferroelectrics possess various physical characteristics such as piezoelectric and pyroelectric effects, which could broaden the application of perovskite ferroelectrics and enhance the optoelectronic performance. Therefore, it is promising to combine multiple effects to optimize the performance of the self-powered PDs. Herein, patterned 2D ferroelectric perovskite (PMA)sub2/subPbClsub4/submicrobelt arrays were demonstrated through a PDMS template-assisted antisolvent crystallization method. The perovskite arrays based flexible photodetectors exhibited fine self-powered photodetection performance under 320 nm illumination and much enhanced reproducibility compared with the randomly distributed single-crystal microbelts-based PDs. Furthermore, by introducing the piezo-phototronic effect, the performance of the flexible PD was greatly enhanced. Under an external tensile strain of 0.71%, the responsivity was enhanced by 185% from 84 to 155.5 mA/W. Our findings offer the advancement of comprehensively utilizing various physical characteristics of the ferroelectrics for novel ferroelectric optoelectronics.

It is well known that monolayer transition-metal dichalcogenides (MX$_2$, M = Mo, W and X = S, Se, Te) could exist in three common structures, i.e. 1$T$, 1$T'$, and 1$H$ phases. In order to reveal their possible phase transitions driven by biaxial strain, we use first-principles calculations to determine the energy landscapes associated with these three phases. Due to its intrinsic dynamical instability, the centrosymmetric 1$T$ phase is known to be metastable and will transform into the 1$T'$ phase where pairs of metal atoms pull together toward each other. Moreover, controlling the metallic 1$T'$ and semiconducting 1$H$ phases is of particular interest as this can introduce novel opportunities in a series of applications. When a biaxial strain is simultaneously compressed along the zigzag direction and stretched along the armchair direction，phase transitions from 1$H$ to 1$T'$ have occurred in MSe$_2$ and MoTe$_2$, but for MSe$_2$ the biaxial strain is much difficult to realize in experiments. For WTe$_2$, the 1$T'$ structure will transform into the 1$H$ form when a biaxial strain is just compressed along the armchair direction. The transitions between 1$H$ and 1$T'$ phases could be attributed to the changes of metal-chalcogen bonds along the armchair direction by analyzing the Crystal Orbital Hamilton Population. Only half M-X bonds along the armchair direction is the main factor, because their lengths are robust in 1$T'$ phase and decrease in 1$H$ form with the tensile strain applied along the armchair direction. Our findings provide a guideline for the phase engineering of transition-metal dichalcogenides with biaxial strain.

This dataset contains the data presented in the Figures of the paperA heterogeneously integrated lithium niobate-on-silicon nitride photonic platform

Photonic integrated circuits are indispensable for data transmission within modern datacenters and pervade into multiple application spheres traditionally limited for bulk optics, such as LiDAR and biosensing1. New applications and higher performance are enabled by the diversification of optical waveguide materials past silicon-on-insulator. Of particular interest are ferroelectrics such as Lithium Niobate, which exhibit a large electro-optical Pockels effect enabling ultrafast and efficient modulation, but are difficult to process via dry etching2. For this reason, etching tightly confining waveguides - routinely achieved in silicon or silicon nitride - has not been possible. Diamond-like carbon (DLC) was discovered in the 1950s 3 and is a material that exhibits an amorphous phase, excellent hardness, and the ability to be deposited in nano-metric thin films. Its use today is pervasive, ranging from applications for hard disk surfaces 4 and medical devices 5 to low friction coatings for automotive components 6. It has excellent thermal, mechanical, and electrical properties, making it an ideal protective coating. Here we demonstrate that DLC is also a superior material for the manufacturing of next-generation photonic integrated circuits based on ferroelectrics, specifically Lithium Niobate on insulator (LNOI). Using DLC as a hard mask, we demonstrate the fabrication of deeply etched, tightly confining, low loss photonic integrated circuits with losses as low as 4 dB/m and Q-factor as high as 10 · 106. In contrast to widely employed ridge waveguides 7,8, this approach benefits from a more than 1 order of magnitude higher area integration density while maintaining efficient electro-optical modulation, low loss, and offering a route for efficient optical fiber interfaces. As a proof of concept, we demonstrate a frequency agile hybrid integrated III-V Lithium Niobate based laser with sub-kHz linewidth and tuning rate of 0.7 Peta-Hertz per second with excellent linearity and CMOS-compatible driving voltage. Our approach can herald a new generation of high density ferroelectric photonic integrated circuits, in particular for applications in coherent laser based ranging 9 and beamforming 10, optical communications 7, and classical 11 and quantum computing networks 12.

Integrated photonics enables signal synthesis, modulation and conversion using photonic integrated circuits (PICs). Many materials have been developed, among which silicon nitride (Si3N4) has emerged as a leading platform particularly for nonlinear photonics. Low-loss Si3N4 PICs have been widely used for frequency comb generation, narrow-linewidth lasers, microwave photonics and photonic computing networks. Yet, among all demonstrated functionalities for Si3N4 integrated photonics, optical non-reciprocal devices such as isolators and circulators have not been achieved. Conventionally, they are realized based on the Faraday effect of magneto-optic materials under an external magnetic field; however, it has been challenging to integrate magneto-optic materials that are not compatible with complementary metal-oxide-semiconductors and that require bulky external magnet. Here we demonstrate a magnetic-free optical isolator based on aluminium nitride (AlN) piezoelectric modulators monolithically integrated on low-loss Si3N4 PICs. The transmission reciprocity is broken by spatio-temporal modulation of a Si3N4 microring resonator with three AlN bulk acoustic wave resonators that are driven with a rotational phase. This design creates an effective rotating acoustic wave that allows indirect interband transition in only one direction among a pair of strongly coupled optical modes. A maximum of 10 dB isolation is achieved under 300 mW total radiofrequency power applied to three actuators, with minimum insertion loss of 0.1 dB. An isolation bandwidth of 700 MHz is obtained, determined by the optical resonance linewidth. The isolation remains constant over nearly 30 dB dynamic range of optical input power, showing excellent optical linearity. Our integrated, linear, magnetic-free, electrically driven optical isolator could be a key building block for integrated lasers and optical interfaces for superconducting circuits., An electrically driven, magnetic-free optical isolator is demonstrated. The device, based on aluminium nitride piezoelectric modulators and a silicon nitride microring resonator, may be useful for integrated lasers and other opto-electric systems.

Here we discuss the wafer-scale fabrication process flow of aluminium airbridges for microwave (MW) interconnects on lithium niobate on Damascene silicon nitride (LNOD) photonic chips. We also discuss the subsequent chip release procedure that preserves the bridges allowing for safe release of these delicate structures.

Silicon photonics enables wafer-scale integration of optical functionalities on chip. Silicon-based laser frequency combs can provide integrated sources of mutually coherent laser lines for terabit-per-second transceivers, parallel coherent light detection and ranging, or photonics-assisted signal processing. We report heterogeneously integrated laser soliton microcombs combining both indium phospide/silicon (InP/Si) semiconductor lasers and ultralow-loss silicon nitride (Si3N4) microresonators on a monolithic silicon substrate. Thousands of devices can be produced from a single wafer by using complementary metal-oxide-semiconductor-compatible techniques. With on-chip electrical control of the laser-microresonator relative optical phase, these devices can output single-soliton microcombs with a 100-gigahertz repetition rate. Furthermore, we observe laser frequency noise reduction due to self-injection locking of the InP/Si laser to the Si3N4 microresonator. Our approach provides a route for large-volume, low-cost manufacturing of narrow-linewidth, chip-based frequency combs for next-generation high-capacity transceivers, data centers, space and mobile platforms.

Erbium-doped fiber amplifiers have revolutionized long-haul optical communications and laser technology. Erbium ions could equally provide a basis for efficient optical amplification in photonic integrated circuits. However, this approach has thus far remained impractical due to insufficient output power. Here, we demonstrate a photonic integrated circuit based erbium amplifier reaching 145 mW output power and more than 30 dB small-signal gain -- on par with commercial fiber amplifiers and beyond state-of-the-art III-V heterogeneously integrated semiconductor amplifiers. We achieve this by applying ion implantation to recently emerged ultralow-loss Si3N4 photonic integrated circuits with meter-scale-length waveguides. We utilize the device to increase by 100-fold the output power of soliton microcombs, required for low-noise photonic microwave generation or as a source for wavelength-division multiplexed optical communications. Endowing Si3N4 photonic integrated circuits with gain enables the miniaturization of a wide range of fiber-based devices such as high-pulse-energy femtosecond mode-locked lasers., Comment: 25 pages, 16 figures

Transition metal oxychlorides (TMOCl) have attracted great attention as promising cathode materials for chloride ion batteries (CIBs). However, current research on TMOCl has been mainly focused on FeOCl and VOCl. On the other hand, the theoretical study of anionic rechargeable batteries faces the difficulty of predicting the discharge voltage of the electrode materials based on the half-cell system. Herein, a reliable theoretical voltage formula for CIBs is proposed based on a full-cell system with Li/LiCl as the reference anode. A high throughput screening method for TMOCl is applied among 16 transition metals. After the screening according to energetic and dynamic stability, Co is identified, which can form a new cathode material of CoOCl. Compared to FeOCl and VOCl, CoOCl has a higher discharge voltage, which is beneficial for achieving a larger energy density. The small crystal field splitting energy and exchange splitting energy of Co3+ result in higher electronic conductivity. In addition, the uniform Cl− binding environment leads to a low Cl− diffusion barrier of 0.37 eV, which is much smaller than that of VOCl (0.65 eV) and FeOCl (0.58 eV).

Discovering efficient and low CO selectivity non-noble heterogeneous catalysts toward formic acid (FA) dehydrogenation is vital for H2 energy systems. As a heating temperature is required to activate this reaction, the strategy of coupling a FA dehydrogenation reactor with a photothermal system possesses great potential for industrial applications. Herein, a sophisticated catalyst, a Mo1.98C1.02 porous film supported on carbon fiber paper, is demonstrated, with the advantages of a porous nanostructure, small nanoparticles and a carbon-supported structure simultaneously. The composite exhibits prominent thermal catalytic FA dehydrogenation, with a CO-free H2 generation rate of 0.79 L g−1 h−1 at 100 °C. Density functional theory calculations show that the formate route (*OCHOH → *OCOH + 1/2H2 → *OCO + 1/2H2 → CO2) is the minimum energy path for H2 and CO2 formation. Besides, a photothermal device was designed based on Bi2Te3/Cu, which can absorb and convert 1 kW m−2 irradiation into a high temperature of 240 °C, due to the high sunlight absorption, low heat conduction and low heat irradiation. Thus, a sunlight-driven thermal catalytic system was designed based on this device, with a H2 generation rate of 1.07 L g−1 h−1 under 0.25 kW m−2. This value is about two orders of magnitude faster than that of photocatalytic FA decomposition over reported non-precious photocatalysts. These results demonstrate that FA dehydrogenation can be realized under weak solar irradiation with the assistance of photothermal systems, facilitating industrial applications.

Discovering efficient and promising non-noble catalysts toward the alkaline hydrogen evolution reaction (HER) is vital for a clean energy system. Here, we design an efficient alkaline HER electroca...

Thermal degradation of the composite constituted by high density polyethylene (HDPE) and microencapsulated red phosphorus (MRP) were studied using thermogravimetric (TG) data obtained at different heating rates. The kinetic models and parameters of the thermal degradation of MRP/HDPE composite were evaluated by FWO, KAS and IKP method. It indicates that the activation energy E of 4 % MRP/HDPE composite is higher than HDPE for three methods. MRP could improve the thermal stability and slow down the thermal degradation of HDPE. With adding MRP, the degradation mechanism of HDPE is changed and the degradation rate decreases.

The phase transitions among polymorphic two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted increasing attention for their potential in enabling distinct functionalities in the same material for making integrated devices. Electron-injection to TMDs has been proved to be a feasible way to drive structural phase transition from the semiconducting H-phase to the semimetal dT-phase. In this contribution, based on density-functional theory (DFT) calculations, firstly we demonstrate that hole-injection drives the transition of the H-phase more efficiently to the metallic T-phase than to the semimetallic dT-phase for group VI-B TMDs (MoS2, WS2, and MoSe2, etc.). The origin can be attributed to the smaller work function of the T-phase than that of the dT-phase. Our work function analysis can distinguish the T and dT phases quantitatively while it is challenging for the commonly used crystal field splitting analysis. In addition, our analysis provides a unified understanding for both hole- and electron-injection induced phase transitions for 2D materials beyond TMDs, such as the newly synthesized MoSi2N4 family. Moreover, the hole-driven T-phase transition mechanism can explain the recent experiment of WS2 phase transition by hole-doping with yttrium (Y) atoms. Using 1/3 Y-doped WS2 and MoSe2 as examples, we show that the Mo and W valency increases to 5+. These above findings open up an avenue to obtain the metallic T-phase, which expands the possible stable phases of 2D materials.

We couple free electrons to optical cavity modes of a chip-based high-Q silicon nitride microresonator and observe single-particle correlations. Mode-specific cathodoluminescence is spatially mapped, and coincidence-gated electron imaging enables a two-orders of magnitude contrast enhancement.

We observe the efficient coupling of free electrons to the optical mode of a chip-integrated high-Q Si3N4 microresonator. This enables strong stimulated inelastic scattering for continuous optical pumping and photon generation for an empty cavity.

We demonstrate efficient microwave-optical frequency conversion using a released HBAR-on-photonic damascene platform. Thermal tuning of coupled optical ring cavities with integrated heaters allows to operate in the triply resonant transduction scheme.

We demonstrate for the first time a hybrid integrated low-noise laser composed of a gallium nitride (GaN) based laser diode and a silicon nitride photonic chip based microresonator operating at record low wavelengths as low as 410 nm in the near ultraviolet wavelength region.

We demonstrate photonic integrated erbium-implanted Si3N4 amplifiers that enable record-high 26 dB on-chip net gain and saturation output power exceeding 25 mW, providing an active Si3N4 nanophotonic platform for integrated lasers, LiDARs and mi-crowave photonics.

We demonstrate an electro-optically tunable hybrid integrated laser self-injection locked to a mode of a heterogeneously integrated lithium-niobate-on-Damascene-silicon-nitride microresonator. An intrinsic linewidth of 3 kHz and a frequency tuning rate of 12 × 1015 Hz/s were observed. Proof-of-principle coherent LiDAR experiments were performed.

We demonstrate a traveling wave parametric amplifier in a photonic Si3N4integrated spiral waveguide of 2.0 m length with footprint 3×5 mm. We achieve net gain of 7 dB on-chip and 2 dB fiber-to-fiber in the optical C-band.

Quantum information, communication, and sensing rely on the generation and control of quantum correlations in complementary degrees of freedom. Free electrons coupled to photonics promise novel hybrid quantum technologies, although single-particle correlations and entanglement have yet to be shown. In this work, we demonstrate the preparation of electron-photon pair states using the phase-matched interaction of free electrons with the evanescent vacuum field of a photonic chip–based optical microresonator. Spontaneous inelastic scattering produces intracavity photons coincident with energy-shifted electrons, which we employ for noise-suppressed optical mode imaging. This parametric pair-state preparation will underpin the future development of free-electron quantum optics, providing a route to quantum-enhanced imaging, electron-photon entanglement, and heralded single-electron and Fock-state photon sources.

Low-loss photonic integrated circuits and microresonators have enabled a wide range of applications, such as narrow-linewidth lasers and chip-scale frequency combs [1] , [2] . To translate these into a widespread technology, attaining ultralow optical losses with established foundry manufacturing is critical. Recent advances in integrated Si 3 N 4 photonics [1] , [3] have shown that ultralow-loss, dispersion-engineered microresonators with quality factors Q > 10×10 6 can be attained at die-level throughput. Yet, current fabrication techniques do not have sufficiently high yield and performance for existing and emerging applications.

Achieving strong coupling of electron beams with single photons and harnessing their potential entanglement promises advancemenets in quantum optics with free-electron, merging spectroscopy of individual quantum systems with the nanoscale spatial resolution available in electron microscopes. Recent experiments on inelastic electron-light scattering (IELS) [1] , [2] with dielectric microcavities such as microspheres [3] or photonic crystal cavities [4] have demonstrated the potential of using resonant field enhancement for increasing the interaction between electrons and photons. IELS with continuous-wave (CW) excitation is, however, challenging due to transition probabilities normally being far below unity [5] .

Wastewater treatment plants (WWTPs) play a vital role in public health because it can emit a large quantity of bioaerosols. Exposure to bioaerosols from WWTPs is a potential health risk to WWTP workers and surrounding residents. In this study, the seasonal fluctuation of aerosolization ratios of several bioaerosols and quantitative health risks of the WWTP workers and the surrounding residents exposed to total coliform, fecal coliform, and enterococcal bioaerosols were analyzed. Results showed that the aerosolization ratio of airborne bacteria was higher in the cold seasons and lower in the warm seasons, whereas the aerosolization ratio of airborne fungi was the highest in summer. The aerosolization ratio of airborne fungi was evidently higher than that of other bioaerosols. Moreover, the aerosolization ratio under the inverted umbrella aerator mode was generally higher than that under the microporous aerator mode. For each exposure scenario, the health risks of males were generally 7.2–26.7% higher than those of females. The health risks of the exposure population exposed to total coliform and enterococcal bioaerosols were generally higher in warm seasons, whereas those of the population exposed to fecal coliform bioaerosol were the highest in winter. Additionally, the health risks of exposure population without masks under the imprudent/conservative estimate all exceeded the benchmarks. However, when equipped with masks, all the exposure populations’ health risks decreased 1–2 orders of magnitude and approached acceptable levels. This research methodically provides new scientific data on the aerosolization ratio of microorganism bioaerosols in a WWTP and promotes the comprehension of their quantitative health risks under imprudent/conservative estimates.

Two-dimensional transition metal dichalcogenides (TMDCs) are promising in spintronics due to their spin–orbit coupling, but their intrinsic non-magnetic properties limit their further development. Here, we focus on the energy landscapes of TMDC (MX2, M = Mo, W and X = S, Se, Te) monolayers by rhenium (Re) substitution doping under axial strains, which controllably drive 1H ↔ 1Td structural transformations. For both 1H and 1Td phases without strain, Re-doped TMDCs have an n-type character and are non-magnetic, but the tensile strain could effectively induce and modulate the magnetism. Specifically, 1H-Re0.5Mo0.5S2 gets a maximum magnetic moment of 0.69 μB at a 6% uniaxial tensile strain along the armchair direction; along the zigzag direction it exhibits a significant magnetic moment (0.49 μB) at a 2.04% uniaxial tensile strain but then exhibits no magnetism in the range of [5.10%, 7.14%]. By contrast, for 1Td-Re0.5Mo0.5S2 a critical uniaxial tensile strain along the zigzag direction reaches up to ∼9.18%, and a smaller uniaxial tensile strain (∼5.10%) along the zigzag direction is needed to induce the magnetism in 1Td-Re0.5M0.5Te2. The results reveal that the magnetism of Re-doped TMDCs could be effectively induced and modulated by the tensile strain, suggesting that strain engineering could have significant applications in doped TMDCs.

Monolayer transition metal dichalcogenides with direct bandgaps are emerging candidates for microelectronics, nano-photonics, and optoelectronics. Transferred onto photonic integrated circuits (PICs), these semiconductor materials have enabled new classes of light-emitting diodes, modulators and photodetectors, that could be amenable to wafer-scale manufacturing. For integrated photonic devices, the optical losses of the PICs are critical. In contrast to silicon, silicon nitride (Si3N4) has emerged as a low-loss integrated platform with a wide transparency window from ultraviolet to mid-infrared and absence of two-photon absorption at telecommunication bands. Moreover, it is suitable for nonlinear integrated photonics due to its high Kerr nonlinearity and high-power handing capability. These features of Si3N4 are intrinsically beneficial for nanophotonics and optoelectronics applications. Here we report a low-loss integrated platform incorporating monolayer molybdenum ditelluride (1L-MoTe2) with Si3N4 photonic microresonators. We show that, with the 1L-MoTe2, microresonator quality factors exceeding 3 million in the telecommunication O-band to E-band are maintained. We further investigate the change of microresonator dispersion and resonance shift due to the presence of 1L-MoTe2, and extrapolate the optical loss introduced by 1L-MoTe2 in the telecommunication bands, out of the excitonic transition region. Our work presents a key step for low-loss, hybrid PICs with layered semiconductors without using heterogeneous wafer bonding.