Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade‐off Optimization

A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type D? C≡C? Pt(PBu₃)₂? C≡C? D (D? Pt? D), A? C≡C? Pt(PBu₃)₂? C≡C? A (A? Pt? A) and D? C≡C? Pt(PBu₃)₂? C≡C? A (D? Pt? A) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade‐offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532 nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with π electron‐accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: D? Pt? D > D? Pt? A > A? Pt? A. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible‐light region and exhibit excellent OPL responses with very impressive figure of merit σ_ex/σ_o values (up to 17), which remarkably outweigh those of state‐of‐the‐art reverse saturable absorption dyes such as C₆₀ and metallophthalocyanines with very poor transparencies. Their lower optical‐limiting thresholds (0.05 J cm^?2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07 J cm^?2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro‐optic sensors.     

Optical properties of (001) GaN/AlN quantum wells

The absorption coefficient and the photoluminescence of (001) GaN/AlN quantum wells are calculated for several values of the well width, with and without the excitonic effect corrections, in the usual monoelectronic approach and as a many-body problem. The calculation was performed considering separate isolated bands for electrons, heavy and light holes. The monoelectronic approach to the optical properties was performed by assuming infinite well walls and finite well walls, respectively. The calculation including the excitonic effect as a many-body problem was performed within a recent approach designed for low-dimensional systems. The different wells studied here present many localized states and a complicated absorption spectrum. The monoelectronic approach in the infinite quantum well approximation reproduces quite well the spectrum of the wide wells due to the fact that the ground states of electrons and holes are well fixed by this model of quantum well.     

Optical clock recovery methods: Review (Invited)

Clock recovery is a fundamental operation in digital telecommunications systems, where the receiver synchronizes itself to the transmitter timing. In optical clock recovery, this operation is made using optical signal processing methods. This paper reviews the physical principles and classifies the various optical clock recovery methods developed during the last 20 years.     

用于光CATV的光功率计

介绍用于光ＣＡＴＶ的光功率计的三种实施方案，并论述各种方案的优缺点。     

Optical Properties of GaN/SiC/por-Si/Si(111) Hybrid Heterostructures

Semiconductors - Using a complex of structural and spectroscopic methods of diagnostics, the influence of a nanoporous-silicon (por-Si) transition layer on the optical properties of GaN layers...     

全息聚合材料PQ/PMMA的光学反应分析

为了探究掺杂有菲醌的聚甲基丙烯酸甲酯(PQ/PMMA)光致聚合材料的光学特性,根据该全息聚合材料基本理论以及内部的光化学反应机制与效应,通过数学方法构建内部反应模型进行仿真与拟合,分析了曝光强度、空间频率对产物、折射指数的影响以及存在的失真效应.结果表明:在给定参数下,曝光强度的最佳选择范围为60～80 mW/cm2,空间频率的相对优化的选择为1 800 lines/mm.     

Inside Front Cover: Environmental Optical Sensitivity of Gold Nanodecahedra (Adv. Funct. Mater. 9/2007)

As reported on p. 1443 by Isabel Pastoriza‐Santos and Luis M. Liz‐Marzán, the high sensitivity of localized surface plasmon resonances towards changes in the refractive index of the surrounding medium for regular gold nanodecahedra render them strong candidates for (bio)sensing applications. Whereas a monolayer of decahedra deposited on a glass slide looks pink in air, it turns blue when immersed in isopropanol. The sensitivity of localized surface plasmon resonances with respect to changes in the refractive index of the surrounding medium is measured for small (< 60 nm side length) and large (ca. 150 nm side length) regular gold nanodecahedra (pentagonal bipyramids), and compared to rigorous solutions of Maxwell's equations for bicones based upon the boundary element method (BEM). Small particles are prepared through ultrasound‐induced reduction of HAuCl₄ by N,N‐dimethylformamide (DMF) on presynthesized penta‐twinned Au seeds, whereas large decahedra are grown using smaller ones as seeds. Excellent agreement between experimental and calculated spectra is found for dispersions and monolayers of particles in different solvents, as well as for the effect of uniform silica layers of various thicknesses grown on them. These results are expected to be useful for the development of novel biosensors.     

星-树枝型光链路光发射功率、分光比及光接收功率的计算与分析

以星-树枝型光链路为例，采用控制末端载噪比和控制末端功率两种方法，分析推导出星-树枝型光链路光分路器分光比和光发射功率的通用公式，并结合实例比较两种计算方法的结果，说明两种设计方法在实际工作中的可行性。     

GaAs/GaAlAs多量子阱自电光效应光学双稳态

采用国产分子束外延系统生长的GaAs/GaAlAs多量子阱材料,成功地制备出室温自电光效应(Self Electrooptic Effect)光学双稳态器件(SEED).报道了这种器件在对称工作(S-SEED)和非对称工作时的光学双稳态特性.     

富勒烯的功率光限幅特性

应用时间分辨技术研究了富勒烯溶液的激发态吸收瞬态功率光限幅特性,在实验条件下,其功率光限幅的开关速度约为5 ns.     

光功率测量的不确定度

本文讨论了影响光功率高精度、准确测量的因素,给出了光纤切割重复性数据、0.85μmLED,1.3μmLED稳定性曲线、光功率计零漂曲线和实测装置的不确定度。     

1.25 Gb/s低功耗CMOS光接收机限幅放大器

设计并实现了用于光纤用户网和千兆以太网光接收机的限幅放大器。电路采用有源电感负载来拓展带宽、稳定直流工作点 ,通过直接耦合技术来提高增益、降低功耗。测试结果表明 ,在从 5 m Vp- p到 5 0 0 m Vp- p,即40 d B的输入动态范围内 ,在 5 0 Ω负载上的单端输出电压摆幅稳定在 2 80 m Vp- p。在 5 V电源电压下 ,功耗仅为1 30 m W。电路可稳定工作在 1 5 5 Mb/s、62 2 Mb/s、1 .2 5 Gb/s三个速率上。     

基于TCP／IP的光功率监测模块的设计与实现

介绍了光功率监测模块的原理,阐述了TCP／IP技术在光功率监测模块（OPM）中的作用以及采用此类技术对监测模块的意义,并给出在实际研发过程中用Socket实现TCP／IP通信的一个例子。