Carnivorous plants inspired shape-morphing slippery surfaces

Carnivorous plants,for instance,Dionaea muscipula and Nepenthes pitcher plant,inspired the innovation of advanced stimuli-responsive actuators and lubricant-infused slippery surfaces,respectively.However,hybrid bionic devices that combine the active and passive prey trapping capabilities of the two kinds of carnivorous plants remain a challenge.Herein,we report a moisture responsive shape-morphing slippery surface that enables both moisture responsive shapemorphing and oil-lubricated water repellency for simultaneous active-and passive-droplet manipulation.The moisture deformable slippery surface is prepared by creating biomimetic microstructures on graphene oxide(GO)membrane via femtosecond laser direct writing and subsequent lubricating with a thin layer of oil on the laser structured reduced GO(LRGO)surface.The integration of a lubricant-infused slippery surface with an LRGO/GO bilayer actuator endows the actuator with droplet sliding ability and promotes the moisture deformation performance due to oil-enhanced water repellency of the inert layer(LRGO).Based on the shape-morphing slippery surface,we prepared a series of proof-of-concept actuators,including a moisture-response Dionaea muscipula actuator,a smart frog tongue,and a smart flower,demonstrating their versatility for active/passive trapping,droplet manipulation,and sensing.

Etching‐assisted femtosecond laser modification of hard materials

With high hardness, high thermal and chemical stability and excellent optical performance, hard materials exhibit great potential applications in various fields, especially in harsh conditions. Femtosecond laser ablation has the capability to fabricate three-dimensional micro/nanostructures in hard materials. However, the low efficiency, low precision and high surface roughness are the main stumbling blocks for femtosecond laser processing of hard materials. So far, etching- assisted femtosecond laser modification has demonstrated to be the efficient strategy to solve the above problems when processing hard materials, including wet etching and dry etching. In this review, femtosecond laser modification that would influence the etching selectivity is introduced. The fundamental and recent applications of the two kinds of etching assisted femtosecond laser modification technologies are summarized. In addition, the challenges and application prospects of these technologies are discussed.

Femtosecond laser fabrication of 3D templates for mass production of artificial compound eyes

Compound eyes are unique optical imaging systems that consist of numerous separate light-sensitive units(ommatidia).Attempts have been made to produce artificial compound eyes via advanced 3 D nanotechnologies.Among them,femtosecond laser direct writing(FsLDW)technology has emerged as an effective strategy due to its distinct advantages in 3 D designable and high precision fabrication capability.However,the point-by-point scanning process results in a very low fabrication efficiency,limiting the practical applications of the FsLDW technology.To solve this problem,we propose a high-efficiency method for the mass production of 3 D artificial compound eyes using a photopolymer template fabricated by FsLDW.The resultant 3 D SU-8 compound eye templates could be used to replicate polydimethylsiloxane(PDMS)compound eyes many times(over 50 times)with a highly improved efficiency(nearly 20 times higher than the efficiency of direct fabrication using the point-by-point FsLDW).The PDMS replicas showed good focusing and imaging performances.We anticipate that this method may serve as an enabler for the mass production of 3 D artificial compound eyes and promote their practical applications in the near future.

Etching-assisted femtosecond laser microfabrication

Although femtosecond laser microfabrication is one of the most promising three-dimensional（3D） fabrication techniques, it could suffer from low fabrication efficiency for structures with high 3D complexities. By using etching as a main assistant technique, the processing can be speeded up and an improved structure surface quality can be provided. However,the assistance of a single technique cannot satisfy the increasing demands of fabrication and integration of highly functional 3D microstructures. Therefore, a multi-technique-based 3D microfabrication method is required. In this paper, we briefly review the recent development on etching-assisted femtosecond laser microfabrication（EAFLM）. Various processing approaches have been proposed to further strengthen the flexibilities of the EAFLM. With the use of the multi-technique-based microfabrication method, 3D microstructure arrays can be rapidly defined on planar or curved surfaces with high structure qualities.

Tunable surface plasmon-polariton resonance in organic light-emitting devices based on corrugated alloy electrodes

We report a feasible method to realize tun able surface plasm on-polarit on(SPP)res onance in orga nic light-emitt ing devices(OLEDs)by emplo ying corrugated Ag-Al alloy electrodes.The excited SPP res onance in duced by the periodic corrugations can be precisely tuned based on the composition ratios of the Ag-Al alloy electrodes.With an appropriate composition ratio of the corrugated alloy electrode,the photons trapped in SPP modes are recovered and extracted effectively.The 25%in creaseme nt in luminance and 21%enhan ceme nt in curre nt efficie ncy have bee n achieved by using the corrugated Ag-Al alloy electrodes in OLEDs.

Laser manufacturing of spatial resolution approaching quantum limit

Atomic and close-to-atom scale manufacturing is a promising avenue toward single-photon emitters,single-electron transistors,single-atom memory,and quantum-bit devices for future communication,computation,and sensing applications.Laser manufacturing is outstanding to this end for ease of beam manipulation,batch production,and no requirement for photomasks.It is,however,suffering from optical diffraction limits.Herein,we report a spatial resolution improved to the quantum limit by exploiting a threshold tracing and lock-in method,whereby the two-order gap between atomic point defect complexes and optical diffraction limit is surpassed,and a feature size of<5 nm is realized.The underlying physics is that the uncertainty of local atom thermal motion dominates electron excitation,rather than the power density slope of the incident laser.We show that the colour centre yield in hexagonal boron nitride is transformed from stochastic to deterministic,and the emission from individual sites becomes polychromatic to monochromatic.As a result,single colour centres in the regular array are deterministically created with a unity yield and high positional accuracy,serving as a step forward for integrated quantum technological applications.

Photon propagation control on laser-written photonic chips enabled by composite waveguides

Femtosecond laser direct writing(Fs LDW)three-dimensional(3D)photonic integrated circuits(PICs)can realize arbitrary arrangement of waveguide arrays and coupling devices.Thus,they are capable of directly constructing arbitrary Hamiltonians and performing specific computing tasks crucial in quantum simulation and computation.However,the propagation constantβis limited to a narrow range in single-mode waveguides by solely changing the processing parameters,which greatly hinders the design of Fs LDW PICs.This study proposes a composite waveguide(CWG)method to increase the range ofβ,where a new single-mode composite waveguide comprises two adjacent circular waveguides.As a result,the photon propagation can be controlled and the variation range ofβcan be efficiently enlarged by approximately two times(Δβ~36 cm-1).With the CWG method,we successfully realize the most compact Fs LDW directional couplers with a 9μm pitch in a straight-line form and achieve the reconstruction of the Hamiltonian of a Hermitian array.Thus,the study represents a step further toward the fine control of the coupling between waveguides and compact integration of Fs LDW PICs.

Photoswitchable quantum electrodynamics in a hybrid plasmonic quantum emitter

The design and preparation of quantum states free from environmen-tal decohering effects is critically important for the development of on-chip quantum systems with robustness.One promising strategy is to harness quantum state superposition to construct decoherence-free subspace(DFS),which is termed dark state.Typically,the exci-tation of dark states relies on anti-phase-matching on two qubits and the inter-qubit distance is of wavelength scale,which limits the de-velopment of compact quantum chips.In the current work,a hybrid plasmonic quantum emitter was proposed,which was composed of strongly correlated quantum emitters intermediated by a plasmonic nanocavity.Through turning the plasmonic loss from drawback into advantage,the anti-phase-matching rule was broken by rapidly de-caying the superposed bright state and preparing a sub-100 nm dark state with decay rate reduced by 3 orders of magnitudes.More inter-estingly,the dark state could be optically switched to a single-photon emitter with enhanced brightness through photon-blockade,with the quantum second order correlation function at zero delay showing a wide range of tunability down to 0.02.

Highly Fluorescent Semiconducting Two-Dimensional Conjugated Polymer Films Achieved by Side-Chain Engineering Showing Large Exciton Diffusion Length

Semiconducting two-dimensional conjugated polymers(2DCPs)with strong fluorescence emission have great potential for various optoelectronic applications.However,it is enormously challenging to achieve this goal due to the significant compact interlayerπ-πstacking-induced quenching effect in these systems.In this work,we found that highly fluorescent semiconducting 2DCPs can be prepared through an effective side-chain engineering approach in which interlayer spacers are introduced to reduce the fluorescence quenching effect.The obtained two truxene-based 2DCP films that,along with-C6H13 and-C_(12)H_(25)alkyl side chains as interlayer spacers both demonstrate superior fluorescence properties with a high photoluminescence quantum yield of 5.6%and 14.6%,respectively.These are among the highest values currently reported for 2DCP films.Moreover,an ultralong isotropic quasi-twodimensional exciton diffusion length constrained in the plane with its highest value approaching 110 nm was revealed by the transient photoluminescence microscopy technique,suggesting that theπ-conjugated structure in these truxene-based 2DCP films has effectively been extended.This work can enable a broad exploration of highly fluorescent semiconducting 2DCP films for more deeply fundamental properties and optoelectronic device applications.

Plasmonic nano-printing: large-area nanoscale energy deposition for efficient surface texturing

The lossy nature of plasmonic wave due to absorption is shown to become an advantage for scaling-up a large area surface nanotexturing of transparent dielectrics and semiconductors by a self-organized sub-wavelength energy deposition leading to an ablation pattern—ripples—using this plasmonic nano-printing.Irreversible nanoscale modifications are delivered by surface plasmon polariton(SPP)using:(i)fast scan and(ii)cylindrical focusing of femtosecond laser pulses for a high patterning throughput.The mechanism of ripple formation on ZnS dielectric is experimentally proven to occur via surface wave at the substrate–plasma interface.The line focusing increase the ordering quality of ripples and facilitates fabrication over wafer-sized areas within a practical time span.Nanoprinting using SPP is expected to open new applications in photo-catalysis,tribology,and solar light harvesting via localized energy deposition rather scattering used in photonic and sensing applications based on re-scattering of SPP modes into far-field modes.

O-FIB:far-field-induced near-field breakdown for direct nanowriting in an atmospheric environment

Nanoscale surface texturing,drilling,cutting,and spatial sculpturing,which are essential for applications,including thin-film solar cells,photonic chips,antireflection,wettability,and friction drag reduction,require not only high accuracy in material processing,but also the capability of manufacturing in an atmospheric environment.Widely used focused ion beam(FIB)technology offers nanoscale precision,but is limited by the vacuum-working conditions;therefore,it is not applicable to industrial-scale samples such as ship hulls or biomaterials,e.g.,cells and tissues.Here,we report an optical far-field-induced near-field breakdown(O-FIB)approach as an optical version of the conventional FIB technique,which allows direct nanowriting in air.The writing is initiated from nanoholes created by femtosecondlaser-induced multiphoton absorption,and its cutting“knife edge”is sharpened by the far-field-regulated enhancement of the optical near field.A spatial resolution of less than 20 nm(λ/40,withλbeing the light wavelength)is readily achieved.O-FIB is empowered by the utilization of simple polarization control of the incident light to steer the nanogroove writing along the designed pattern.The universality of near-field enhancement and localization makes O-FIB applicable to various materials,and enables a large-area printing mode that is superior to conventional FIB processing.

Protein-based soft micro-optics fabricated by femtosecond laser direct writing

In this work,we report a novel soft diffractive micro-optics,called‘microscale kinoform phase-type lens(micro-KPL)’,which is fabricated by femtosecond laser direct writing(FsLDW)using bovine serum albumin(BSA)as building blocks and flexible polydimethylsiloxane(PDMS)slices as substrates.By carefully optimizing various process parameters of FsLDW(e.g.,average laser power density,scanning step,exposure time on a single point and protein concentration),the as-formed protein micro-KPLs exhibit excellent surface quality,well-defined three-dimensional(3D)geometry and distinctive optical properties,even in relatively harsh operation environments(for instance,in strong acid or base).Laser shaping,imaging and other optical performances can be easily achieved.More importantly,micro-KPLs also have unique flexible and stretchable properties as well as good biocompatibility and biodegradability.Therefore,such protein hydrogel-based micro-optics may have great potential applications,such as in flexible and stretchable photonics and optics,soft integrated optical microsystems and bioimplantable devices.

Mechanically robust stretchable organic optoelectronic devices built using a simple and universal stencil-pattern transferring technology

Stretchable electronic and optoelectronic devices based on controllable ordered buckling structures exhibit superior mechanical stability by retaining their buckling profile without distortion in repeated stretch-release cycles.However,a simple and universal technology to introduce ordered buckling structures into stretchable devices remains a real challenge.Here,a simple and general stencil-pattern transferring technology was applied to stretchable organic lightemitting devices(SOLEDs)and polymer solar cells(SPSCs)to realize an ordered buckling profile.To the best of our knowledge,both the SOLEDs and SPSCs with periodic buckles exhibited the highest mechanical robustness by operating with small performance variations after 20,000 and 12,000 stretch-release cycles between 0%and 20%tensile strain,respectively.Notably,in this work,periodic-buckled structures were introduced into SPSCs for the first time,with the number of stretch-release cycles for the SPSCs improved by two orders of magnitude compared to that for previously reported random-buckled stretchable organic solar cells.The simple method used in this work provides a universal solution for low-cost and high-performance stretchable electronic and optoelectronic devices and promotes the commercial development of stretchable devices in wearable electronics.

Ultrafast optical spectroscopy of surface-modified silicon quantum dots: unraveling the underlying mechanism of the ultrabright and color-tunable photoluminescence

In this work,the fundamental mechanism of ultrabright fluorescence from surface-modified colloidal silicon quantum dots is investigated in depth using ultrafast spectroscopy.The underlying energy band structure corresponding to such highly efficient direct bandgap-like emissions in our surface-modified silicon quantum dots is unraveled by analyzing the transient optical spectrum,which demonstrates the significant effect of surface molecular engineering.It is observed that special surface modification,which creates novel surface states,is responsible for the different emission wavelengths and the significant improvement in the photoluminescence quantum yields.Following this essential understanding,surface-modified silicon quantum dots with deep blue to orange emission are successfully prepared without changing their sizes.

Laser fabrication of graphene-based supercapacitors

Supercapacitors(SCs)have broad applications in wearable electronics(e.g.,e-skin,robots).Recently,graphenebased supercapacitors(G-SCs)have attracted extensive attention for their excellent flexibility and electrochemical performance.Laser fabrication of G-SCs exhibits obvious superiority because of the simple procedures and integration compatibility with future electronics.Here,we comprehensively summarize the state-of-the-art advancements in laser-assisted preparation of G-SCs,including working mechanisms,fabrication procedures,and unique characteristics.In the working mechanism section,electric double-layer capacitors and pseudocapacitors are introduced.The latest advancements in this field are comprehensively summarized,including laser reduction of graphene oxides,laser treatment of graphene prepared from chemical vapor deposition,and laserinduced graphene.In addition,the unique characteristics of laser-enabled G-SCs,such as structured graphene,graphene hybrids,and heteroatom doping graphene-related electrodes,are presented.Subsequently,laser-enabled miniaturized,stretchable,and integrated G-SCs are also discussed.It is anticipated that laser fabrication of G-SCs holds great promise for developing future energy storage devices.

Time-dependent density-functional theory molecular-dynamics study on amorphization of Sc-Sb-Te alloy under optical excitation

Recently,all-optical memory and optical-computation properties of phase-change materials are receiving intensive attention.Because writing/erasing information in these devices is usually achieved by laser pulses,the interaction between the laser and the phase-change materials becomes a key issue for such new applications.In this work,by a time-dependent density-functional theory molecular-dynamics study,the physics underlying the optical excitation induced amorphization of Sc-Sb-Te is revealed,which goes back to superatom-like Sc-centered structural motifs.These motifs are found to be still robust under the excitation.

Heterogeneous self-healing assembly of MXene and graphene oxide enables producing free-standing and self-reparable soft electronics and robots

Self-healing materials(SHMs)with unique mechanical and electronic properties are promising for self-reparable electronics and robots.However,the self-healing ability of emerging two-dimensional(2D)materials,for instance,MXenes,has not been systematically investigated,which limits their applications in self-healing electronics.Herein,we report the homogeneous self-healing assembly(homoSHA)of MXene and the heterogeneous self-healing assembly(hetero-SHA)of MXene and graphene oxide(GO)under moisture treatments.The self-healing mechanism has been attributed to the hydration induced interlayer swelling of MXene and GO and the recombination of hydrogen bond networks after water desorption.The multiform hetero-SHA of MXene and GO not only enables facile fabrication of free-standing soft electronics and robots,but also endows the resultant devices with damage-healing properties.As proof-of-concept demonstrations,free-standing soft electronic devices including a generator,a humidity sensor,a pressure sensor,and several robotic devices have been fabricated.The hetero-SHA of MXene and GO is simple yet effective,and it may pioneer a new avenue to develop miniature soft electronics and robots based on 2D materials.

Two-dimensional In_(2)Se_(3):A rising advanced material for ferroelectric data storage

Ferroelectric memory is a promising candidate for next-generation nonvolatile memory owing to its outstanding performance such as low power consump-tion,fast speed,and high endurance.However,the ferroelectricity of conven-tional ferroelectric materials will be eliminated by the depolarization field when the size drops to the nanometer scale.As a result,the miniaturization of ferroelectric devices was hindered,which makes ferroelectric memory unable to keep up with the development of integrated-circuit(IC)miniaturization.Recently,a two-dimensional(2D)In2Se3 was reported to maintain stable ferro-electricity at the ultrathin scale,which is expected to break through the bottle-neck of miniaturization.Soon,devices based on 2D In2Se3,including the ferroelectric field-effect transistor,ferroelectric channel transistor,synaptic fer-roelectric semiconductor junction,and ferroelectric memristor were demon-strated.However,a comprehensive understanding of the structures and the ferroelectric-switching mechanism of 2D In2Se3 is still lacking.Here,the atomic structures of different phases,the dynamic mechanism of ferroelectric switching,and the performance/functions of the latest devices of 2D In2Se3 are reviewed.Furthermore,the correlations among the structures,the properties,and the device performance are analyzed.Finally,several crucial problems or challenges and possible research directions are put forward.We hope that this review paper can provide timely knowledge and help for the research commu-nity to develop 2D In2Se3 based ferroelectric memory and computing technol-ogy for practical industrial applications.

The mystical interlinks:Mechanics,religion or optics?

The beauty of this world relies on a fact that there is always this or that mystical interlink among different fields, one concept in a specific realm shines out with great brilliancy in another totally different territory. Catenary is the curve that a free-hanging chain assumes under its own weight, which is thought to be a ＂true mathematical and mechanical form＂ in architecture. The catenary shape could also be found in the silk of a spider＇s web, but no significant phe- nomena have ever been observed in optics.

Highly aligned organic microwire crystal arrays for high-performance polarization-sensitive photodetectors and image sensors

Organic semiconductors with excellent optoelectronic properties are important building blocks for highperformance organic devices.Patterning organic crystals with high precision and accurately positioning them at the target position are major challenges for integrated devices.However,uncontrollable dewetting of the conventional solution method leads to as-prepared micro-nanocrystals with high defect-state density,low crystalline quality,and disordered distribution,which impair the uniformity of the device performance and limit integration.By regulating the solution position with a template and guiding the solution flow direction under gravity,aligned organic microwire arrays and polygonal patterns were fabricated.The polarization-sensitive photodetector exhibited responsivity up to 1234 A W^(-1),linear dynamic range of 148 dB,I_(photo)/I_(dark)of 10^(4),response time as low as 1.1 ms,and dichroic ratio up to 2.1.Given the homogeneity of microwire arrays,the device-to-device variation was reduced to 3.58%,resulting in high-quality imaging.This study provides new insights into organic micro/nanocrystal patterning and device integration.