LP modes exchange based on multiplane light conversion

Data exchange between different mode channels is essential in the optical communication network with mode-division multiplexing(MDM).However,there are challenges in realizing mode exchange with low insert loss,low mode crosstalk,and high integration.Here,we designed and fabricated a mode exchange device based on multiplane light conversion(MPLC),which supports the transmission of LP01,LP11a,LP11b,and LP21 modes in the C-band and L-band.The simulated exchanged mode purities are greater than 85%.The phase masks were fabricated on a silicon substrate to facilitate the integration with optical systems,with an insert loss of less than 2.2 dB and mode crosstalk below-21 dB due primarily to machining inaccuracies and alignment errors.We carried out an optical communication experiment with 10 Gbit/s OOK and QPSK data transmission at the wavelength of 1550 nm and obtained excellent performance with the device.It paves the way for flexible data exchange as a building block in MDM optical communication networks.

Luminescence properties of composite material Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)/light conversion agent with multilayer structure

In order to improve the red luminescent properties,Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)was selected as a blue persistent luminescent donor phosphor,while light conversion agent was utilized to tune the persistent luminescent spectra from blue to red.Composite red luminescent material Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)/light conversion agent(SMED/LCA)was fabricated with light conversion agent and Sr_(2)MgSi_(2)O_(7):Eu^(2+),Dy^(3+)at a certain mass ratio.SiO_(2)(Al2 O_(3) or MgF2)were coated on the surface of SMED/LCA through heterogeneous deposition method.The structural and optical characteristics of the resulting samples were launched in terms of X-ray diffraction and emission spectrum as well as afterglow brightness.The results demonstrate that the emission spectrum exhibits two emission bands,and the peaks are located at around 470 and 615 nm.SiO_(2),Al_(2)O_(3) and MgF_(2) are coated on the surface of SMED/LCA like a protective shell to maintain its stability and luminescent properties,the afterglow initial brightness is still up to 0.37 cd/m^(2) and the afterglow color purity calculated from CIE color coordinates is basically unchanged.

Effect of light conversion agent on luminous properties of a new down-converting material SrAl_2O_4:Eu^(2+),Dy^(3+)/light conversion agent

A new luminous material SrAl2O4：Eu^2＋,Dy^3＋/light conversion agent that can emit red light in the darkness after being excited was fabricated by combining light conversion agent on to SrAl2O4：Eu^2＋,Dy^3＋ particles through YsiX3.The morphology of the luminous materials was analyzed by scan electron microscopy（SEM）.The emission behavior was evaluated by fluorescence spectrophotometric analysis and the results demonstrated that the emission spectra of samples had a redshift compared to SrAl2O4：Eu^2＋,Dy^3＋ and the emission intensity rose dramatically at first and then decreased when the ratio of light conversion agent doping was over 1.4 wt.%.And the emission color of SrAl2O4：Eu^2＋,Dy^3＋/light conversion agent was tuned from green（SrAl2O4：Eu^2＋,Dy^3＋）to orange-red.Furthermore,the afterglow property was also investigated,and the results indicated that the afterglow brightness reached 6.5 cd/m^2,and as the light conversion agent concentration increased the brightness intensity decreased.

Luminescence properties of SrB_4_O_7:Sm^(2+) for light conversion agent

A deep red-emitting SrB407：Sm^2＋ phosphor for light conversion agent was synthesized by the conventional solid-state reaction. X-ray powder diffraction （XRD） analysis confirmed the phase formation of SrB4OT：Sm^2＋ materials. Results of luminescence properties showed that the phosphor could be efficiently excited by the UV-vis light region from 250-500 nm, and it exhibited deep red （685 nm） emis- sion corresponding to ^5D0→^7F0 transition of Sm^2＋. The critical quenching concentration of Sm^2＋ in SrB407：Sm^2＋ phosphor was about 0.05, and the corresponding concentration quenching mechanism was verified to be the dipole-dipole interaction according to the Dexter＇s theory. The decay times had few alterations with different concentrations in SrB4OT：xZm^2＋ phosphor.

Light energy conversion device for photocatalyst 2.0%WO_3-TiO_2 with oxygen vacancies for water splitting

Using carbon felt, polytetrafluoroethylene latex and powder catalyst to assembly a light energy conversion device, the photocatalytic activity of catalyst 2.0%WO3-TiO2 （2%WO3 compounding TiO2） with oxygen vacancies was studied through the water splitting for O2 evolution, using a high pressure mercury lamp as the light source and Fe^3＋ as the electron acceptor in two different devices： an ordinary photolysis device with catalyst powder suspending through a magnetic stirrer and a self-assembly light energy conversion device. The results show that after 12 h irradiation, the photocatalytic activity of 2.0%WO3-TiO2 with oxygen vacancies in the self-assembly light energy conversion device is higher than that of the ordinary photolysis device, and the amount of oxygen evolution is about 12 and 9 mmol/L respectively in these two devices. After 12 h, the rates of 02 evolution are slow in each device and the photocatalyst almost loses the photoactivity in the ordinary photolysis device. So, compared with the ordinary photocatalytic device, the rate of oxygen evolution and the life time of the catalyst are improved in the self-assembly light energy conversion device.

Photoinhibition and Photooxidation in Leaves of indica and japonica Rice Under Different Temperatures and Light Intensities

Physiological indices related to the efficiency (F-v/F-m) of light energy conversion in PS II and the peroxidation of membrane lipid were measured in leaves of Oryza sativa L. sp. indica rice cv. 'Shanyou 63' and sp. japonica rice cv. '9516'' under different temperatures and fight intensities for 4 days. No changes in F-v/F-m and membrane lipid peroxidation product (MDA) were observed, so neither photoinhibition nor photooxidation happened in both rice cultivars under moderate temperature and medium light intensity. However, F-v/F-m dropped obviously with no change in MDA contents, and photoinhibition appeared in indica rice cv. 'Shanyou 63' under medium temperature and strong light intensity. Furthermore, both photoinhibition and photooxidation were observed in two rice cultivars under chilling temperature and strong light intensity. Experiments with inhibitors under chilling temperature and strong light intensity showed that indica rice had a decrease in DI protein content and SOD activity, and the extent of inhibition of xanthophyll. cycle and nonphotochemical quenching (qN) was larger, and a higher level of MDA was observed. The photoinhibition and photooxidation in indica rice were more distinct as compared with japonica rice. The authors suggested that PS II light energy conversion efficiency (F-v/F-m) and membrane lipid peroxidation were the key indices for the detection of photooxidation.

Layered-stacking of titania films for solar energy conversion:Toward tailored optical,electronic and photovoltaic performance

Nanostructured TiO2 with differentiate morphologies has attracted tremendous attention due to its wide band-gap nature as well as outstanding optical and electric properties for solar-driven light-toelectricity conversion application. Layered-stacking TiO2 film such as double-layer, tri-layer, quadrupleor quintuplicate-layer, is highly desirable to the design of high-performance semiconductor material photoanodes and the development of advanced photovoltaic devices. In this minireview, we will summarize the recent progress and achievements on proof-of-concept of layered-stacking TiO2 films（LTFs） for solar cells with emphasis on the tailored properties and synergistic functionalization of LTFs, such as optimized sensitizer adsorption, broadened light confinement as well as facilitated electron transport characteristics.Various demonstrations of LTFs photovoltaic systems provide lots of possibilities and flexibilities for more efficient solar energy utilization that a wide variety of TiO2 with distinguished morphologies can be integrated into differently structured photoanodes with synergistic and complementary advantages. This key structure engineering technology will also pave the way for the development of next generation state-ofthe-art electronics and optoelectronics. Finally, from our point of view, we conclude the future research interest and efforts for constructing more efficient LTFs as photoelectrode, which will be highly warranted to advance the solar energy conversion process.

Azimuthal beam shaping in orbital angular momentum basis

Shaping the light beam is always essential for laser technology and its applications.Among the shaping technologies,shaping the laser in its Fourier domain is a widely used and effective method,such as a pulse shaper,or a 4f system with a phase mask or an iris in between.Orbital angular momentum(OAM)modes spectrum,the Fourier transform of the light field in azimuth,provides a perspective for shaping the light.Here,we propose and experimentally demonstrate a shaping strategy for the azimuthal field by modulating the complex amplitude of the OAM mode spectrum.The scheme utilizes multi-plane light conversion technology and consists only of a spatial light modulator and a mirror.Multiple functions,including beam rotating,beam splitting/combining in azimuth,and OAM mode filtering,are demonstrated.Our work provides a compact and programmable solution for modulating the OAM mode spectrum and shaping beams in azimuth.

Highly enhanced visible-light photocatalytic NOx purification and conversion pathway on self-structurally modified g-C-3N4 nanosheets

The unmodified graphitic carbon nitride(g-C_3N_4) suffers from low photocatalytic activity because of the unfavourable structure.In the present work,we reported a simple self-structural modification strategy to optimize the microstructure of g-C_3N_4 and obtained graphene-like g-C_3N_4 nanosheets with porous structure.In contrast to traditional thermal pyrolysis preparation of g-C_3N_4,the present thermal condensation was improved via pyrolysis of thiourea in an alumina crucible without a cover,followed by secondary heat treatment.The popcorn-like formation and layer-by-layer thermal exfoliation of graphene-like porous g-C_3N_4 was proposed to explain the formation mechanism.The photocatalytic removal performance of both NO and NO_2 with the graphene-like porous g-C_3N_4 for was significantly enhanced by selfstructural modification.Trapping experiments and in-situ diffuse reflectance infrared fourier transform spectroscopy(DRIFTS) measurement were conducted to detect the active species during photocatalysis and the conversion pathway of g-C_3N_4 photocatalysis for NO_x purification was revealed.The photocatalytic activity of graphene-like porous g-C_3N_4 was highly enhanced due to the improved charge separation and increased oxidation capacity of the ·O_2^- radicals and holes.This work could not only provide a novel self-structural modification for design of highly efficient photocatalysts,but also offer new insights into the mechanistic understanding of g-C_3N_4 photocatalysis.

Photonic lattice-like waveguides in glass directly written by femtosecond laser for on-chip mode conversion

We report on a conceptually new type of waveguide in glass by femtosecond laser direct writing,namely,photonic latticelike waveguide(PLLW).The PLLWfs core consists of well-distributed and densified tracks with a sub-micron size of 0.62μm in width.Specifically,a PLLW inscribed as hexagonal-shape input with a ring-shape output side was implemented to converse Gaussian mode to doughnut-like mode,and high conversion efficiency was obtained with a low insertion loss of 1.65 dB at 976 nm.This work provides a new freedom for design and fabrication of the refractive index profile of waveguides with sub-micron resolution and broadens the functionalities and application scenarios of femtosecond laser direct-writing waveguides in future 3D integrated photonic systems.

Advances in luminescent lanthanide complexes and applications

Luminescent lanthanide complexes have been widely investigated as light emitting materials in bio-imaging and sensing, solid state lighting and display, anti-fake tags and light conversion films, due to their characterized photophysical properties including large Stokes shift, long lifetime, and sharp emission spectrum, arising from the sensitized f-f transitions. In this review, we summarize the most recent advances in luminescent lanthanide complexes and their applications from 2015 to August 2017 concerning of general concepts to potential applications. We first introduce the basic concept of sensitized luminescence of lanthanide complexes and the strategies used for highly luminescent complexes. Then recent varieties of luminescent lanthanide complexes and their hybrid materials are presented. Finally, applications are discussed in detail.