Propagation properties of stochastic electromagnetic double-vortex beams in a turbulent atmosphere

Based on the extended Huygens-Fresnel principle, we study the propagation properties of stochastic electromagnetic double-vortex beams in a turbulent atmosphere. The result shows that the spreading of partially coherent double-vortex beams can be smaller than that of fully coherent ones. The degree of polarization of this kind of beam will experience change, which is dependent on the degree of polarization of the source plane, the atmospheric turbulence, topological charge, and the spatial coherence. The results may have applications in space optical communication.

Propagation dynamics and experimental observation of quadratic vortex beam

The concept of a quadratic vortex beam is proposed, in which phase term of the beam is given by exp（i mθ2）. The phase of the quadratic vortex beam increases with azimuthal angle nonlinearly. This change in phase produces several unexpected effects. Unlike the circularly symmetric beam spot of normal vortex beams, the intensity distribution of the quadratic vortex beam is shown to be asymmetric. The phase singularities will shift in the transverse beam plane on propagation.

Optical Torque Exerted on a Rotator under Illumination of a Vortex Beam

We investigate the torque on a specially shaped rotator produced by a vortex beam.The formulas for the torque along x,y and z directions axe derived,and numerical calculation is performed.It is found that for the specially shaped rotator,the torque brought by the Laguerre-Gauss (LG) vortex beam is dependent upon the angle of the facet for each part of the rotator,and the topological charge of the vortex beam.It is shown that torque is generated from both the light momentum and orbital angular momentum (OAM) of the incident vortex beam,indicating that we can control the rotation of the rotator by modulating the OAM of the incident light beam.

Spectral spatial coherence of high-power multi-chip LEDs

We investigate the spatial coherence of the light generated from high-power multi-chip red LEDs by using the van Cittert-Zernike theorem.It is theoretically demonstrated that the light generated from multi-chip LEDs evolves into partially coherent light after propagation,and the spatial coherence is increased with the increase of propagation distance.Moreover,the spatial coherence of the light is found to be closely related to the chip distribution of multi-chip LEDs.The distribution of the spatial coherence of the light is experimentally examined by Young's double-slit interference.It is found that the experimental results are consistent with the theoretical ones.

Rapid, automated, and reliable antimicrobial susceptibility test from positive blood culture by CAST‐R

Antimicrobial susceptibility tests(ASTs)are pivotal in combating multidrug resistant pathogens,yet they can be time‐consuming,labor‐intensive,and unstable.Using the AST of tigecycline for sepsis as the main model,here we establish an automated system of Clinical Antimicrobials Susceptibility Test Ramanometry(CAST‐R),based on D2O‐probed Raman microspectroscopy.Featuring a liquid robot for sample pretreatment and a machine learning‐based control scheme for data acquisition and quality control,the 3‐h,automated CAST‐R process accelerates AST by>10‐fold,processes 96 paralleled antibiotic‐exposure reactions,and produces high‐quality Raman spectra.The Expedited Minimal Inhibitory Concentration via Metabolic Activity is proposed as a quantitative and broadly applicable parameter for metabolism‐based AST,which shows 99%essential agreement and 93%categorical agreement with the broth microdilution method(BMD)when tested on 100 Acinetobacter baumannii isolates.Further tests on 26 clinically positive blood samples for eight antimicrobials,including tigecycline,meropenem,ceftazidime,ampicillin/sulbactam,oxacillin,clindamycin,vancomycin,and levofloxacin reveal 93%categorical agreement with BMD‐based results.The automation,speed,reliability,and general applicability of CAST‐R suggest its potential utility for guiding the clinical administration of antimicrobials.

Laser-induced plasma and laser-induced breakdown spectroscopy （LIBS） in China： The challenge and the opportunity

Laser-induced plasma as a spectroscopic emission source was introduced only two years after the invention of the laser. By focusing a pulse delivered by a ruby laser on the surface of a solid target, Brech and Cross in 1962 first observed optical emission following the laser impact , which later had been further identified as the emission from the plasma produced during the laser ablation process of the impacted target.

A wavelength division multiplexer based on plastic surface-relief grating applied to local area communication network

A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication.