Atomic optical spatial mode extractor for vector beams based on polarization-dependent absorption

Vector beams with spiral phase and spatially varying polarization profiles have many applications from optical micromanipulation to materials processing. Here, we propose and demonstrate an atomic spatial mode extracting scheme for the vector beam based on polarization-dependent absorption in the atom vapor. By employing the linear polarization pump beam which induces polarization sensitive absorption in the atomic ensemble, a counter-propagated weak probe vector beam is extracted by spatial absorption, and extracted part still maintains the original polarization and the vortex phase.The topological charges of the extracted mode are verified by interfering with the Gaussian beam, and it can be found that the orbital angular momentum is conserved in the extracting process. Our work will have potential applications in non-destructive spatial mode identification, and is also useful for studying higher-dimensional quantum information based on atomic ensembles.

A novel bio‑active microsphere for meniscus regeneration via inducing cell migration and chondrocyte differentiation

Abstract Meniscus injury is a common disease in clinic.If it was not treated in time,it leads to osteoarthritis which brings unbearable pain and heavy economic burden to the patients.At present,meniscectomy and meniscus suture are widely used in the treatment for meniscus injury.Nevertheless,It is not ideal for poor self-healing ability of meniscus.The recruitment of endogenous stem cells is an attractive option for wounded meniscus healing.Fully reduced high-mobility group box 1 protein(HMGB1)can accelerate the regeneration of multiple tissues by endogenous stem cell activation,migration and differentiation.Kartogenin(KGN)has shown to induce the chondrogenesis of the stem cells.However,no study has explored such effects of HMGB1 and KGN in wounded meniscus healing.Therefore,in order to improve the regeneration of meniscus,we intend to use a novel bioactive microsphere which was developed by combining fully reduced high mobility group box 1(frHMGB1)and kartogenin(KGN)with alginate gel which slowly release high concentrations of HMGB1 and KGN to activate rat bone marrow stem cells(BMSCs)and promote cell proliferation.The results showed that this HMGB1–KGN microsphere released and kept high concentrations of HMGB1 and KGN in the wound area for more than 2 weeks.In vitro experimental results showed that the HMGB1–KGN microsphere can promote cell proliferation via recruiting rat bone marrow stem cells(BMSCs)and activating the BMSCs from G_(0) to G_(Alert) stage as evidenced by cell migration testing and 5-bromo-2′-deoxyuridine(BrdU)incorporation assay.In vivo results indicated that this HMGB-KGN microsphere can recruit GFP-labeled BMSCs from tail vein to wounded meniscus and induce these GFP-labeled BMSCs to differentiate into chondrocytes.Our results demonstrated that the HMGB1–KGN-containing bioactive microsphere induced cell migration in vitro and recruited the cells to wound area to promote wounded rat meniscus healing in vivo.

Optically spatial information selection with hybridly polarized beam in atomic vapor

Vector beams with spatially variant polarization have attracted much attention in recent years, with potential applications in both classical optics and quantum optics. In this work, we study a polarization selection of spatial intensity distribution by utilizing a hybridly polarized beam as a coupling beam and a circularly polarized beam as a probe beam in87 Rb atom vapor. We experimentally observe that the spatial intensity distribution of the probe beam after passing through atoms can be modulated by the hybridly polarized beam due to the optical pumping effect. Then, the information loaded in the probe beam can be designedly filtrated by an atomic system with a high extinction ratio. A detailed process of the optical pumping effect in our configurations and the corresponding absorption spectra are presented to interpret our experimental results, which can be used for the spatial optical information locally extracted based on an atomic system, which has potential applications in quantum communication and computation.

External-force-driven solution epitaxy of large-area 2D organic single crystals for high-performance field-effect transistors

Growth of two-dimensional(2D)organic single crystals(2DOSCs)on water surface has attracted increasing attention,because it can serve as a molecularly flat and defect-free substrate.However,large-area growth of 2DOSCs with controllable crystal orientation on water surface remains a key challenge.Herein,we develop a simple method,i.e.external-force-driven solution epitaxy(EFDSE),for the large-area growth of 2DOSCs at air/water interface.Using 2,7-didecylbenzothienobenzothiophene(C1o-BTBT)as an example,high-quality 2D C10-BTBT crystals on centimeter scale are generated by directionally controlling the spreading of organic solution on water surface with external force.Benefiting from the controllable crystal orientation with optimal charge transport,the corresponding 2DOSC-based organic field-effect transistors(OFETs)exhibit a high carrier mobility of 13.5 cm^2·V^-1·s^-1(effective mobility=5.4 cm^2·V^-1·s^-1 according to a reliability factor of 40%),which represents the best result achieved for water-surface-assembled 2DOSC based OFETs.Furthermore,by transterring the C1o-BTBT 2DOSCs to flexible substrates,devices with excellent bending stability are achieved.It is anticipated that our method will provide new insight into the controllable growth of large-area 2DOSCs for high-performance organic devices.

Linking observation,modelling and satellite-based estimation of global land evapotranspiration

Evapotranspiration(ET)is a pivotal process for ecosystem water budgets and accounts for a substantial portion of the global energy balance.In this paper,the exited actual ETmain datasets in global scale,and the global ET modeling and estimates were focused on discussion.The Source energy balance(SEB)models,empirical models and other process-based models are summarized.Accuracy for ET estimates by SEBmodels highly depends on accurate surface temperature retrieval,and SEB models are hard to apply in large heterogeneous surface.The Penman-Monteith(PM)equations are thought to be with considerable sound mechanism.However,it involves large number of parameters,which are not all global available.A simplified PM equation by Priestley and Taylor(PT)is found to perform well on well-watered surface.For both PM and PT equations in estimating ET,the key is to consider the constraint from surface resistance primarily water stress.Empiricalmodels are simple but the accuracy of which highly depends on training samples.Coupling satellite data into ET models can improve ET estimates with higher resolution spatiotemporal information inputs;However,finding the most proper way to estimate global ET remains problematic.Several reasons for this issue are also analyzed in this review.

Visualization of magnetic fields with cylindrical vector beams in a warm atomic vapor

We propose and demonstrate an experimental implementation for the observation of magnetic fields from spatial features of absorption profiles in a warm atomic vapor.A radially polarized vector beam that traverses atomic vapor will generate an absorption pattern with a petal-like structure by the mediation of a transverse magnetic field(TMF).The spatial absorption pattern rotates when the azimuthal angle of the TMF is changed,while its contrast decreases when the longitudinal component of the magnetic field increases.By analyzing the intensity distribution of the transmitted pattern,we can determine the magnetic field strength.Our work provides a framework for investigating 3 D magnetic field distributions based on atoms.

Controllable speckle compression in atomic vapor by frequency modulation and its application in ghost imaging

An image undergoes a paraxial diffraction spreading when propagating in free space.The reduction of diffraction is critical for many potential applications[1-3].Recently,it has been recognized that optical diffraction can be greatly suppressed or even eliminated by using atomic coherence effects[4-9].Several experimental attempts to extent the