Design and analysis of a high efficiency linear power amplifier

A high efficiency linear power amplifier is introduced based on the idea of Switch-Linear Hybrid (SLH) power conversion. The SLH power amplifier developed from the conventional class B power amplifier, while the class B configuration power unit in the SLH power amplifier is fed by a dynamic switching power supply, not the usual constant DC power supply. Thus, the efficiency of the class B configuration power unit in SLH power amplifier can be greatly improved. By combining linear power amplifier with switching power supply, the SLH power amplifier has synthetic performance of high fidelity, high efficiency and excellent dynamic characteristics. In this article, analysis of SLH power amplifier is performed, especially focusing on its linear power unit which is the core of SLH power amplifier. Design considerations are also presented parallel with the analysis. Both the theoretical analysis and experimental results verify the validity of SLH power amplifier.     

1030nm高重复频率纳秒脉冲全光纤放大器

采用脉冲调制的单模带尾纤输出的半导体激光器作为种子源,以掺镱光纤为增益介质,采用主振荡功率放大(MOPA)结构,实现了1030nm全光纤脉冲激光放大。脉冲重复频率在50～100kHz范围内可调,在重复频率50kHz时,实现了脉冲宽度为6.53ns,峰值功率为16.08kW的脉冲输出,相应的斜率效率为69%,输出激光的中心波长在1029.49nm。实验还研究了不同重复频率下输出激光脉冲的时域特性。该激光器的输出波长在激光雷达探测器的光谱响应范围内,可作为激光雷达发射光源。     

新的偶氮类有机共轭化合物的合成及三阶非线性光学性能

设计合成了6个新的偶氮类有机共轭化合物,用傅里叶变换红外光谱仪(FT-IR),1H核磁共振(1H NMR)和元素分析确证了结构.采用飞秒激光,运用简并四波混频(DFWM)法,研究了化合物在非共振状态下的三阶非线性光学(NLO)性能.它们的三阶非线性光学极化率x(3)为(3.31～3.96)×10-13 esu,非线性折射率n2为(6.08～7.27)×10-12esu,分子二阶超极化率γ为(3.44～4.11)×10-31 esu,响应时间τ为102～111 fs.探索了化合物的分子结构对三阶非线性光学性能的影响.引入离域能小的芳杂环,增长共轭链,形成吸供构型,增大取代基的供电子能力,提高共轭体系的共平面程度等因素,有利于获得较大的三阶非线性光学性能.     

Al-free cladding-layer blue laser diodes with a low aspect ratio in far-field beam pattern

c-plane GaN-based blue laser diodes (LDs) were fabricated with Al-free cladding layers (CLs) and deepened etching depth of mesa structure,so the aspect ratio of the far-field pattern (FFP) of the laser beam can be reduced to as low as 1.7,which is nearly the same as conventional AlGaInP-based red LDs.By using GaN CLs,the radiation angle of the laser beam θ(T) is only 10.1 ° in the direction perpendicular to the junction plane.After forming a deeply etched mesa,the beam divergence angle parallel to the junction plane of FFP,θ//,increases from 4.9° to 5.8°.After using the modified structure,the operation voltage of LD is effectively reduced by 2 V at an injection current of 50 mA,but the threshold current value increases.The etching damage may be one of the main reasons responsible for the increase of the threshold current.     

Solvent‐Assisted Low‐Temperature Crystallization of SnO2 Electron‐Transfer Layer for High‐Efficiency Planar Perovskite Solar Cells

A high‐quality polycrystalline SnO₂ electron‐transfer layer is synthesized through an in situ, low‐temperature, and unique butanol–water solvent‐assisted process. By choosing a mixture of butanol and water as a solvent, the crystallinity is enhanced and the crystallization temperature is lowered to 130 °C, making the process fully compatible with flexible plastic substrates. The best solar cells fabricated using these layers achieve an efficiency of 20.52% (average 19.02%) which is among the best in the class of planar n–i–p‐type perovskite (MAPbI₃) solar cells. The strongly reduced crystallization temperature of the materials allows their use on a flexible substrate, with a resulting device efficiency of 18%.     

测量激光束横模结构的方法研究

分析了根据激光场强度相对分布计算激光束横模结构的方法,根据分析结果设计了利用光场分布测量激光束横模结构的实验方法。对所设计的方法进行了仿真验证,同时通过具体实验,对一款调Q激光二极管抽运固体激光器(DPL)的激光束横模结构进行了测量。实验中,在不知道谐振腔参数的情况下,根据设计的方法测量了激光束的各阶横模比例。以测量出的横模比例为基础,理论上重构出激光束,该光束和实际光束的空间传输过程基本吻合。     

误码条件下Turbo码编码参数的盲识别

针对误码条件下的Turbo码的盲识别问题,提出了一种新的码流局域搜索的识别算法。该方法利用分量编码器中寄存器数量有限这一特点,建立了包含编码器结构的编码多项式库,从而通过快速搜索得到分量编码器的结构。仿真实验表明了该算法的正确性与有效性。     

低相干光干涉法延时测量中的误差分析

低相干光干涉法通过测量宽谱光通过待测器件之后的相位变化得到其相对延时量。采集宽谱光时域干涉数据,利用傅里叶变换提取出频域相位信息后再进行相位展开、多项式拟合处理,所得相位曲线对频率求导可得待测延时曲线。延时测量误差来源于干涉信号强度误差和纯相位误差。理论分析和仿真计算表明,延时误差与相位误差成正比;强度噪声引起的相位误差与噪声强度成正比,且该类噪声可通过曲线拟合算法得到有效抑制。实验表明,温度等环境因素引起的纯相位误差是延时测量误差的主要因素。实验上,对约19 m光子晶体光纤于1540~1560 nm波段的相对延时进行了测量,达到了0.14 ps的精度。     

基于智慧因子的分布式可穿戴音频人体网络随机微分博弈功率控制模型

In this study, aiming at the characteristics of randomness and dynamics in Wearable Audio-o-riented BodyNets(WA-BodyNets), stochastic differ-ential game theory is applied to the investigation of the problem of transmitted power control inconsum-er electronic devices. First, astochastic differential game model is proposed for non-cooperative decen-tralized uplink power control with a wisdom regula-tion factor over WA-BodyNets with a one-hop star topology.This model aims to minimize the cost as-sociated with the novel payoff function of a player, for which two cost functions are defined: functions of inherent power radiation and accumulated power radiation damage. Second, the feedback Nash equi-librium solution of the proposed model and the con-straint of the Quality of Service (QoS) requirement of the player based on the SIR threshold are derived by solving the Fleming-Bellman-Isaacs partial dif-ferential equations. Furthermore, the Markov prop-erty of the optimal feedback strategies in this model is verified.The simulation results show that the pro-posed game model is effective and feasible for con-trolling the transmitted power of WA-BodyNets.     

Te掺杂超宽带隙隧穿结研究

研究制备得到峰值电流密度为65.3A/cm2的GaInP/AlGaAs宽带隙隧穿结和峰值电流密度为6.1A/cm2的AlGaInP/AlGaAs超宽带隙隧穿结。在隧穿结中使用二乙基碲（DETe）作为n型掺杂剂,实验中研究了材料生长温度、阀门开关处理以及DETe的流量等生长参数。采用预掺杂和升温后处理的方式来解决碲源的开关效应,而Te掺杂引入的晶格失配采用应力平衡技术来消除。另外研究了不同DETe流量下制备得到的隧穿结性能。