汽车用导光体导光效率研究

汽车内诸如各类开关背光、工作指示、氛围灯等光照均匀性及亮度效果的达成,通常都依赖于导光体。导光体通常由透明塑料(如PC、PMMA等)制作而成,且导光体会被弯曲成各种各样的角度,以契合不同位置的光照效果。然而,其弯折角度与截面尺寸会对导光体的导光效率产生作用。文章将分别把弯折角度、截面半径设定为独立变量,探究二者对导光效率的具体影响,并归纳其中的规律,用于指导导光体的结构设计。

基于COMSOL Multiphysics模拟树脂透光混凝土的导光体参数对透光性能的影响

树脂作为树脂透光混凝土中的导光体,是影响树脂透光混凝土透光性能的主要构件。为了更加全面地研究各参数对导光体透光性能的影响,基于有限元仿真模拟软件COMSOL Multiphysics,对导光体在相互平行的直射光下的透光率变化进行了模拟研究;并且计算了树脂透光混凝土的有效照度分数。结果表明,水泥砂浆壁面的反射率、光线的入射角以及导光体长度和半径都会影响树脂透光混凝土的透光率。水泥砂浆壁面的反射率越大,入射角越大,导光体长度越长、半径越小,则透光率越大。光线的入射角对导光体的透光率较大;当反射率从0增加到0.6时,导光体透光率的增长不明显,透光率的增加量均<2%。而当反射率>0.6后,导光体透光率开始明显增大,并且增长速率也随之增大。太阳入射角对导光体的透光率影响较大,导致了树脂透光混凝土的有效照度分数普遍低于55%。

基于导光体技术的一种多用途舞台灯光设计方案

本文介绍了一种基于导光体技术的多用途舞台灯光学系统变换的设计方案。结合理论基础和实践应用,通过相关光学仿真软件分析了基于导光体技术的多用途舞台灯的变换光学系统的光学效率、照度、光斑均匀度等效果。结果显示,配合光源和导光体的机械运动,可实现舞台灯在不同场合需求的光束、图案的效果,即光斑中心亮度和均匀度的自动变换。分析结果很好的解决了现有气泡灯光源光束灯要求中心照度高和图案灯要求光斑均匀度的矛盾,也验证了光线在导光体发生3-5次反射后能很好的平衡光学效率和光斑均匀度之间的矛盾。

透光混凝土在岭南地区博物馆中的应用

本文旨在论述岭南地区博物馆应用新型透光混凝土墙板的相关施工工艺,通过材料实验分析和总结透光混凝土的透光性能、抗压强度、抗渗透性等技术指标,并探究透光混凝土墙板干挂安装机构和施工工艺,提高干挂透光混凝土墙板的施工效率和效果,并减少安装机构对光源的干涉和不利影响。最后通过DEST等节能软件模拟分析、试验和监测博物馆内外光源效果,探索智能化的监测光源方法。通过一系列模拟分析和试验研究,为保证博物馆外立面墙板强度,导光体材料体积比需保证不超过3%。同时,墙板固定装置与导光体位置协调,使用BIM软件建模模拟“碰撞”,防止重叠干涉,保证透光率达到设计要求。透光混凝土需做好导光体和混凝土的接触界面处理,平衡整体力学性能和透光率的取舍,导光体数量增加会导致接触界面增加,会减弱混凝土的内部强度和耐久性能。

Characteristic analysis of 1.06μm long-cavity diode lasers based on asymmetric waveguide structures

In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power at high injection currents.In this paper,a simplified numerical analysis model is proposed for 1.06μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional(1D)rate equations.The ef⁃fects of LSHB,TPA and FCA on the output characteristics are systematically analyzed,and it is proposed that ad⁃justing the front facet reflectivity and the position of the quantum well(QW)in the waveguide layer can improve the front facet output power.

Polycondensation of ammonium thiocyanate into novel porous g-C_3N_4 nanosheets as photocatalysts for enhanced hydrogen evolution under visible light irradiation

Porous graphitic carbon nitride（pg-C3N4） nanosheets have been prepared through a one-step ammonia thermopolymerization method.The effects of synthetic temperature on the structural,optical and photocatalytic properties of the samples have been investigated.Characterization results show that the heptazine-based conjugate heterocyclic structure was formed over 500℃,which is attributed to the inhibitory effect of ammonia from the decomposition of NH4SCN.Precise nanosheet morphology and an increased pore distribution with an enlarged surface area are observed for the samples obtained under high temperatures.Optical analysis results show that the bandgap of the samples widens and photoluminescene intensity is gradually quenched as the treating temperature is increased.The results demonstrate that a higher polymerization temperature improves the nanolayer structure,porosity and migration rate of the photo-induced carriers of the samples.The pg-C3N4 nanosheets prepared at 600℃ presents the highest photocatalytic activity for hydrogen evolution from water under visible-light irradiation.This study demonstrates a novel strategy for the synthesis and optimization of polymer semiconductor nanosheets with gratifying photocatalytic performance.

Quantitative Moisture Measurement with a Cavity Ring-down Spectrometer using Telecom Diode Lasers

Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using different absorption lines of H20 in the 1.56 and 1.36 gm regions, we are able to determine the relative concentration （mole fraction） of water vapor from a few percent down to the 10-12 level. The quantitative accuracy is examined by comparing the CRDS hygrometer with a commercial chilled-mirror dew-point meter. The high sensitivity of the CRDS instrument allows a water detection limit of 8 pptv.

All-Optical Sampling Using Nonlinear Polarization Rotation in a Single Semiconductor Optical Amplifier

We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.

Application of Padé Approximation in Simulating Photonic Crystals

To save finite-difference time-domain（FDTD） computing time, several methods are proposed to convert the time domain FDTD output into frequency domain. The Pad6 approximation with Baker＇s algorithm and the program are introduced to simulate photonic crystal structures. For a simple pole system with frequency 160THz and quality factor of 5000, the intensity spectrum obtained by the Padé approximation from a 2^8-item sequence output is more exact than that obtained by fast Fourier transformation from a 2^20-item sequence output. The mode frequencies and quality factors are calculated at different wave vectors for the photonic crystal slab from a much shorter FDTD output than that required by the FFT method, and then the band diagrams are obatined. In addition, mode frequencies and Q-factors are calculated for photonic crystal microcavity.

A New Process for Improving Performance of VCSELs

A new process method is proposed to improve the light output power of GaAs vertical cavity surface-emitting lasers （VCSELs）. The VCSELs with open-annulus-distributed holes have a light output power 1.34 times higher than those with ring trenches. The 14μm-aperture devices have a light output power higher than 10mW and have a maximum of 12.48mW at 29.6mA. In addition,open-annulus-distributed holes offer bridges for current injection,so the connecting Ti-Au metal between the ohmic contact and bonding pad does not have to cross the ring trench, and it therefore would not cause the connecting metal to be broken. These VCSELs also show high-temperature operation capabilities,and they have a maximum output power of 8mW even at an operation temperature of up to 60℃.

Investigation of 980nm Ridge Waveguide Lasers with Current Non-Injection Regions by He Ion Implantaion

The technology of He ion implantation for improving the catastrophic optical damage (COD) level of 980nm semiconductor lasers is introduced.After He ion implantation,p-GaAs obtain higher resistivity than before.About 25μm-long current non-injection regions are introduced near both facets,where the injection current is blocked by high resistivity area.The current non-injection regions can reduce carriers inject to facets,and the rate of the non-radiative recombination are reduced.So the COD level is higher than before.The He ion implantation LDs exhibit no COD failure until the rollover occure at a mean maximum power of 440.5mW.Mean COD level of conventional LDs is given as 407.5mW.Compared to conventional LDs,the mean maximum output power level of He ion implantation LDs is improved by 8%.

A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor

We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.

1.3μm AlInGaAs Strained Single Quantum Well Laser Diodes with High Characteristic Temperature of 200K

A high characteristic temperature （T0） of 200K from a 1.3μm AlInGaAs/AlInAs single-quantum-well laser diode with the asymmetric waveguide layer structure under CW operation at 20 to 80℃ was obtained,which is the best result reported in the laser diodes （LDs） of the same active materials structure and emitting wave- length. AllnGaAs as an active layer,therefore,is very promising for the fabrication of long-wavelength LDs with excellent high-temperature performance. It is found that the asymmetric waveguide layer structure can decrease optical absorption and improve the high-temperature performance and catastrophic optical damage threshold of LDs.

Effect of DBR Geometry on Reflectivity and Spectral Linewidth of DBR Lasers

The linewidths of InGaAs-GaAs-AlGaAs DBR lasers with varied DBR dimensional parameters are measured and analyzed. These lasers were built with different DBR grating lengths and depths in order to explore the effect of the size of the DBR on its coupling coefficient and reflectivity,and hence on the linewidth of the laser diodes. The linewidths were measured by employing a self heterodyne linewidth measurement system. The experimental and calculated data for DBR reflectivity and spectral linewidth are given. The relationship between these data and the dimensions of the DBR is analyzed. Based on this analysis,the effect of the DBR geometry on the linewidth of the lasers is explored. The results give useful information related to the design and fabrication of such DBR lasers.

Study and Fabrication of a Au/n-ZnO/p-Si Structure UV-Enhanced Phototransistor

The fabrication and characterization of a Schottky-emitter heterojunction-collector UV-enhanced bipolar phototransistor （SHBT） are presented. The luminescence peak of the ZnO film is observed at 371nm in the PL spectrum. The sensitivity of the ultraviolet response from 200 to 400nm is enhanced noticeably, and the spectrum response at wavelengths longer than 400nm is also retained, The experiments show that the Au/n-ZnO/p-Si SHBT UV enhanced phototransistor enhances the sensitivity of the ultraviolet response noticeably. The UV response sensitivity at 370nm of the phototransistor is 5-10 times that of a ZnO/Si heterojunction UV enhanced photodiode.

Monolithic Integration of a Widely Tunable Laser with SOA Using Quantum-Well Intermixing

This paper presents an SG-DBR with a monolithically integrated SOA fabricated using quantum-well intermixing （QWI） for the first time in China's Mainland. The wavelength tuning range covers 33nm and the output power reaches 10mW with an SOA current of 50mA. The device can work at available channels with SMSR over 35dB.

A Single Mode980 nm In Ga As/Ga As/Al Ga As Large Optical Cavity Quantum Well Laser with Low Vertical Divergence Angle

To achieve high optical power as well as low vertical divergence angle,a new kind of optim ized large opti- cal cavity (L OC) structure is applied to a ridge waveguide 980 nm In Ga As/ Ga As/ Al Ga As m ulti- quantum well laser.The optical power density in the waveguide is successfully reduced.The maxim um output power is more than 40 0 m W with a slope efficiency of 0 .89W/ A and the far- field vertical divergence angle is lowered to 2 3°.

SYNTHESIS AND PHOTOELECTRIC PROPERTIES OF PERYLENE RED PIGMENTS

A series of N, N′ dialkyl (and aryl) perylene 3,4:9, 10 bis (dicarboximide) compounds were prepared and purified, and their photoelectric properties as organic photoconductors were explored. It is found that N, N′ dimethyl perylene 3,4:9, 10 bis (dicarboximide) and perylene 3,4:9,10 tetracarboxylic acid bisbenzimidazole show excellent photoconductivities, their charge acceptance reaches 700 V and 485 V, and the photosensitivity is 45 lx·s and 10 lx·s with dark decays 70 and 60 V/s respectively. The introduction of chlorine atoms can improve their photoelectric properties. SEM analyses also show that the dispersion of pigment in OPC could affect its photosensitivity.

Design of Tensile Strained InGaAsP/InGaAsP MQW for 1.55μm Polarization Independent Semiconductor Optical Amplifier

The theoretical optimization of tensile strained InGaAsP/InGaAsP MQW for 1.55μm windows polarization-independent semiconductor optical amplifier is reported.The valence-band structure of the MQW is calculated by using k·p method,in which 6×6 Luttinger effective-mass Hamiltonian is taken into account.The polarization dependent optical gain is calculated with various well width,strain,and carrier density.

Monolithically Integrated Laser Diode and Electroabsorption Modulator with Dual-Waveguide Spot-Size Converter Output

A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The devices emit in a single transverse and quasi single longitudinal mode with an SMSR of 25.6dB.These devices exhibit a 3dB modulation bandwidth of 15.0GHz,and modulator DC extinction ratios of 16.2dB.The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 7.3°×18.0°,respectively,resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.