Frequency Stabilization of Pulsed Injection-Seeded OPO Based on Optical Heterodyne Technique

A frequency stabilizing system for a pulsed injection seeded 1550 nm optical parametric oscillator(OPO) at 20 Hz repetition rate is demonstrated.The optical heterodyne method is used to measure the frequency difference between the seed laser and the OPO output.Using the frequency difference as the error signal,a proportionalintegral controller in combination with a scanner is applied to stably match the OPO cavity length to the seed laser frequency.The root-mean-square(rms) error of the frequency discrimination method is 0.07 MHz according to a ‘frequency shifting-chopping-beat' evaluation.The frequency fluctuation of the frequency-stabilized OPO is0.29 MHz(rms),and the Allan deviation is less than 20 k Hz for averaging time of more than 3 s.     

太阳能草坪灯控制系统研究与设计

设计了一款低功耗、高性能的以STM32为核心的太阳能草坪灯控制系统,阐述了系统的工作原理和软硬件电路设计。该系统具有防过充、防过放、自动开启和关闭草坪灯的功能。将光敏元件采集到的信号送到STM32,由STM32自带的ADC实现对输入信号多通道同步模数转换,根据光照强度控制照明电路。蓄电池是太阳能草坪灯的唯一电源,通过限定其两端的电压,防止过充、过放,有效地保护蓄电池,延长其使用寿命。     

基于长程气体吸收池的单频纳秒脉冲激光光谱纯度测量

基于长程气体吸收池技术,搭建了针对波长为1572 nm的单频激光的光谱纯度测量装置,理论分析了测量精度的影响因素,并推导出误差计算公式。结果表明,该装置可精确测量光谱纯度为90%～99.999%的激光输出。使用该装置对1572 nm种子注入光参量振荡器输出的单频纳秒脉冲进行测量,测得其光谱纯度为(99.996±0.0005)%,达到工业应用的要求。     

VoLTE语音端到端问题自动定位方法研究

本文主要介绍实现终端测试数据与核心网多种接口XDR数据进行同步关联的算法。利用对VoLTE通话异常原因的定位技术,指导VoLTE客户感知问题的发现、定界。研究成果可快速将VoLTE问题分配到归口部门进行解决,快速提升用户语音业务感知。     

Compact first and second order polarization mode dispersion emulator

Polarization mode dispersion (PMD) is becoming major system impairment in high speed and long distance opti- cal fiber transmission systems. Since the PMD-induced pulse spreading is a frequency-dependent statistic pa- rameter and varies randomly over time, it is difficult to be compensated[1-3]. Large length of single mode opti- cal fiber is needed to generate certain amount of PMD in laboratory, and the PMD effect in the fiber varies slightly and slowly over time. Therefore, PMD emula- …     

Impact of polarization dependent loss on degree of polarization as feedback signal of polarization mode dispersion

Polarization dependent loss (PDL) has been recognized as a critical issue because various inline optical components may have nonnegligible PDL effect that interacts with polarization mode dispersion (PMD). We investigated the impact of PMD-PDL interaction on degree of polarization (DOP), which is the most commonly used feedback signal in PMD compensation. The simulation results of a 40-Gb/s NRZ code optical transmission system show that the maximum PMD increases from approximately 40 ps to more than 45 ps, while minimum DOP declines from approximately 0.6 to approximately 0.2. The interaction of PMD and PDL also induces residual PMD underestimation of 5-8 ps, which causes degradation of PMD compensation performance.     

地方院校半导体物理实验教学的改革实践

半导体物理实验是专门为半导体物理所开设的实验课程,在培养高质量半导体人才的过程中起着关键作用。本文分析了目前半导体物理实验开设现状,针对地方院校特点,结合我校多年实践经验,从实验教师队伍、实验设备、实验教学内容、实验教学方法、实验考核方式、实验安全等方面对半导体物理实验进行了一系列改革。实践结果表明,在地方院校师资、经费受限的情况下,实验教学效果良好。结果可供其他开设半导体物理实验的地方院校参考。     

Laser-diode-pumped zigzag slab Nd:YAG master oscillator power amplifier

A high-repetition rate master oscillator power amplifier pumped with laser diodes (LDs) is reported. An injection seeding single-frequency electro-optical Q-switched Nd:YAG laser is used as an oscillator, and a conductively cooled Nd:YAG zigzag slab with a bounce-pumped architecture is utilized as a power amplifier. Pulse energies of over 800 mJ at 1 064 nm and 400 mJ at 532 nm, corresponding to average powers of 200 and 100 W, respectively, are achieved with a 12.6-ns pulse width at 250 Hz. Output frequency fluctuations and single-frequency operation are further monitored. Experimental results reveal that the proposed system, which features a single-pass amplified configuration, is a promising design for space-based applications.     

直驱永磁同步风力发电系统控制技术综述

本文对风力机的建模及其特性模拟的方法进行了分析,结合直驱永磁同步风力发电系统的拓扑结构,重点分析和比较了机组的最优功率输出控制技术以及变换器的控制策略,并阐述了机组在低电压穿越时的控制方案,最后根据风电场接入电网后对电网的影响,探讨了几种提高电能质量和电网稳定性的措施。     

一种安全计算机板级测试系统的设计与实现

针对铁路安全计算机,根据板级测试的基本原则,结合计算机辅助测试技术,构建安全计算机板级测试平台,解决了电源可靠受控,测试激励信号控制的问题,根据主要的板级软件测试流程,设计并实现了综合板级测试系统。该系统已获得实际应用,实践证明该系统稳定可靠,可以实现对多类型板级测试的目的,并且有效检测出电路设计中的错误,大大提高了产品出厂的测试效率。