掺铒光纤放大器增益和噪声研究

文章首先介绍了掺铒光纤放大器(EDFA)的结构和工作原理,然后运用能级理论和激光原理,深入全面地分析了影响EDFA增益和噪声的主要因素,得出了EDFA增益和噪声与泵浦功率、泵浦方式、输入信号光功率和掺铒光纤长度等关系的一些重要结论,并且通过实验进一步验证了这些结论;提出了提高EDFA增益,减小噪声系数的方法;最后根据文中得出的结论,设计了一种高增益低噪声的C波段EDFA光路,该光路已经应用于工程实践中.     

利用Optisystem仿真研究EDFA增益的影响因素

利用Optisystem软件建立EDFA系统,对EDFA增益的影响因素进行了分析.通过系统仿真分析,根据影响EDFA增益的因素,确定影响EDFA增益的最佳因素参数,验证了EDFA仿真系统的正确性和设计方案的可行性,更加准确地得到最佳优化设计方案.     

几种新型的掺铒光纤放大器

概述了近年来掺铒光纤放大器 (EDFA)的技术发展 ,着重介绍了单泵两级 EDFA、远泵浦 EDFA、增益均衡或增益锁定 EDFA三种新颖的原理结构 ,为未来实用的优化 EDFA提供一些参考。     

反向泵浦光纤拉曼放大器的实现与传输实验

文章设计并实现了C L波段4泵浦光纤拉曼放大器(FRA),讨论了泵浦驱动电路的设计及掺铒光纤放大器(EDFA)与FRA 150 km混合传输的传输性能.实验结果表明,驱动电路可以稳定可靠地工作,当拉曼放大器的增益＜5 dB时,信号的误码性能不会得到显著提高.实验结果可为EDFA与FRA混合传输系统中增益的配置提供参考.     

由Giles模型对L-band EDFA的理论分析

本文通过运用Giles模型对L-band EDFA在不同泵浦波长下的增益、不同泵浦功率与光纤长度的关系以及各种增益特性等进行了数值模拟,并同时辅以C-band EDFA进行比较计算,从理论上对L-band EDFA的特性进行了较为详细的分析说明,并得出了一些新颖的结论。     

基于FBG的高转换效率的L-band EDFA的研究

本文对基于FBG的L—band EDFA进行了实验研究。通过在光路中加入FBG反射铒纤的后向ASE,980nm和1480nm泵浦的L—band EDFA的泵浦转换效率都有了明显的提高。加入FBG后,在1570～1600nm的30nm波长范围内,980nm泵浦功率为72mW时,平均增益13.7dB,增益起伏在小于±0.25dB;1480nm泵浦功率为39mW时,平均增益17.5dB,增益起伏小于±1.5dB。通过我们的实验证明这一结构的L—band EDFA是简单高效的。     

全光增益钳制掺铒光纤放大器的瞬态特性研究

利用数值模拟方法对全光增益筘制EDFA的瞬态特性进行了系统的理论分析,着重研究了瞬态过程中系统参量（泵浦功率、环路损耗、上下载速度、上下载信道功率、钳制激光振荡波长等）对剩余信道驰豫振荡特性的影响;根据数值模拟结果,给出了全光增益箝制EDFA的优化设计思路。     

由Giles模型对L-band EDFA的理论分析

本文通过运用Giles模型对L—band EDFA在不同泵浦波长下的增益、不同泵浦功率与光纤长度的关系以及各种增益特性等进行了数值模拟，并同时辅以C—band EDFA进行比较计算，从理论上对L-band EDFA的特性进行了较为详细的分析说明，并得出了一些新颖的结论。     

输入信号功率对EDFA增益斜率的影响

研究输入信号功率对掺铒光纤放大器(EDFA)增益斜率的影响,可为EDFA的优化设计提供理论参考.采用了实验分析和数值模拟两种方法,在EDF长度为14 m,输入波长为1530～1562 nm,泵浦光功率为400mW时,对输入信号功率为-5～5 dBm的EDFA增益斜率进行了对比,发现随着输入信号功率的增大,增益斜率也逐渐...     

基于掺铒光纤放大器的布里渊光时域反射仪的研究

为了提高布里渊光时域反射仪(BOTDR)的传感长度和系统分辨率,分析了基于掺铒光纤放大器(EDFA)的BOTDR性能。研究表明,在被测光纤中,反向泵浦的EDFA在增益和噪声指数方面优于正向泵浦;未使用EDFA的BOTDR测得光纤长约为50km,而利用EDFA的BDTDR测量的距离大于80km;反向泵浦和正向泵浦的温度分辨率分别为0.5℃和1.0℃。结果表明,反向泵浦的BDTDR的性能高于正向泵浦。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its