也谈光电耦合器

光电耦合器是以光为媒介传输电信号的一种电-光-电转换器件。它由发光源和受光器两部分组成。把发光源和受光器组装在同一密闭的壳体内，彼此间用透明绝缘体隔离。发光源的引脚为输入端，受光器的引脚为输出端。常见的发光源为发光二极管。受光器为光敏二极管、光敏三极管等等。光电耦合器的种类较多。

1.5μm Self-Aligned Spotsize Converter Integrated DFB Fabricated by Selective Area Grown MOVPE

High performance 1 57μm spotsize converter monolithically integrated DFB is fabricated by the technique of self aligned selective area growth.The upper optical confinement layer and the butt coupled tapered thickness waveguide are regrown simultaneously,which not only offeres the separated optimization of the active region and the integrated spotsize converter,but also reduces the difficulty of the butt joint selective regrowth.The threshold current is as low as 4 4mA.The output power at 49mA is 10 1mW.The side mode suppression ratio (SMSR) is 33 2dB.The vertical and horizontal far field divergence angles are as small as 9° and 15° respectively,the 1dB misalignment tolerance are 3 6μm and 3 4μm.

Temperature dependence of excitonic transition in ZnSe/ZnCdSe quantum wells

A theoretical calculation for the temperature dependence of the excitonic transition in ZnSe/ZnOdSe quantum wells is performed. The exciton binding energy is calculated with a variational technique by considering the temperature-dependence parameters. Our results show that the exciton binding energy reduces linearly with temperature increasing. We find that the strain due to lattice mismatch and differential thermal expansion decreases with the temperature increasing.

Hybrid WDM/TDM PON system employing an all-optical wavelength converter

A new hybrid WDM/TDM passive optical network （PON） implemented by using all-optical wavelength converters （AOWCs） is proposed. The AOWCs are based on the cross-gain modulation （XGM） effect of the semiconductor optical amplifier （SOA）. Moreover, the feasibility of this sys- tem is experimentally demonstrated by evaluating the impacts of the optical wavelength conversion, time domain waveforms, eye diagrams and bit-error-rate （BER） in AOWC. The results show that the proposal will be a promising solution for the next generation access networks.

Focal Plane Image Assembly of Subpixel

This paper describes the scanning assembly principle and construction of scanning assembly sample.The factors that affect assembly accuracy are analyzed.There are two steps in CCD focal plane scanning assembly.The first is rough assembly,and the second is accurate assembly.In this paper,the moiré fringe is introduced in judging assembly accuracy directly and accurately.The equation for optical transmission characteristics of CCD Moiré fringes is presented.The measurement of Moiré fringes can be completed when some conditions are satisfied.2D_assembly error can be obtained by using digital correlation filtering technique.Finally,the result of focal plane scanning assembly is presented.The result is in good accordance with theory.

Furan-based liquid-crystalline small-molecule donor guest improving the photovoltaic performance of organic solar cells with amorphous packing

Introducing liquid-crystalline small-molecule donors(SMDs)into binary systems based on the strong intermolecular interactions of SMDs is a facile and effective strategy to tune the active layer morphology and improve the performance of organic solar cells(OSCs).Contrary to conventional understanding,this research proposes a new strategy for ternary OSCs implicating that"weakly crystalline materials can also optimize the morphology of the active layer and improve the OSCs performance".Herein,we designed and synthesized two liquid-crystalline SMDs,Z1 and Z2,based on benzodifuran(BDF)units.The amorphous Z2-incorporated ternary devices present an unexpectedly improved power conversion efficiency(PCE)>18%with good stability.By contrast,the highly ordered Z1-based ternary devices possess a significantly depressed efficiency.Multiple characterizations reveal that the Z2-based ternary blend films possess improved miscibility and efficient charge transport.This novel strategy for the selection of the third component is significant for the fabrication of high-efficiency ternary OSCs.

CsPbBrI perovskites with low energy loss for high-performance indoor and outdoor photovoltaics

Over the years,the efficiency of inorganic perovskite solar cells(PSCs)has increased at an unprecedented pace.However,energy loss in the device has limited a further increase in efficiency and commercialization.In this work,we used(NH4)2C2O4·H2O to treat CsPbBrI2 perovskite film during spin-coating.The CsPbBrI2 underwent secondary crystallization to form high quality films with micrometer-scale and low trap density.(NH4)2C2O4·H2O treatment promoted charge transfer capacity and reduced the ideal factor.It also dropped the energy loss from 0.80 to 0.64 eV.The resulting device delivered a power conversion efficiency(PCE)of 16.55%with an open-circuit voltage(Voc)of 1.24 V,which are largely improved compared with the reference device which exhibited a PCE of 13.27%and a Voc of 1.10 V.In addition,the optimized treated device presented a record indoor PCE of 28.48%under a fluorescent lamp of 1000 lux,better than that of the reference device(19.05%).

Effect of annealing treatment on the performance of organic photovoltaic devices using SPFGraphene as electron-accepter material

We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT：PSS/P3OT：PCBM-SPFGraphene/LiF/A1. Given the P3OT/PCBM （1：1） mixture with 8wt% of SPFGraphene, the open-circuit voltage （Voc） of the device reaches 0.64 V, a short-circuit current density （J^c） reaches 5.7 mA/cm2, a fill factor （FF） reaches 0.42, and the power conversion efficiency （7？） reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement In the P3OT：PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital （LUMO）-SPFGraphene-A1. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital （HOMO） and LUMO of the donoffacceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180℃ show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.