Phase-related noise characteristics of 780 nm band single-frequency lasers used in the cold atomic clock

We propose a method to directly measure phase-related noise characteristics of single-frequency lasers in the 728–980 nm band based on a 120°phase difference interferometer.Differential phase information of the laser under test is demodulated via the interferometer.Other parameters related to the phase noise characteristics such as linewidth at different observation time, phase/frequency noise, power spectrum density of phase/frequency fluctuation, and Allan deviation are further obtained.Frequency noise as low as 1 Hz^2/Hz can be measured using our system.Then the phase-related noise characteristics of two commercial lasers frequently used in cold atomic clocks are studied systematically by the method.Furthermore, several influencing factors and their relative evolution laws are also revealed, such as the pump current and frequency-locking control parameters.This would help to optimize the laser performance, select laser sources, and evaluate the system performance for cold atomic physics applications.

浅谈“互联网+”背景下的亲子阅读活动

3~6岁是幼儿阅读能力发展的关键期,这一时期的幼儿大脑迅速发展,开始认识符号,对各种符号和文字感兴趣,对语言有着敏锐的吸收和存储能力,并愿意积极尝试运用语言来描述自己的所见所闻。阅读是所有学习能力的基础,只有打好坚实的阅读基础,孩子将来的学习才能得到保证。苏霍姆林斯基曾经说过:“孩子的阅读开始越早,阅读时思维过程越复杂,阅读时对智力发展就越有益。”因此,在幼儿园阶段开展有效的亲子阅读是提高幼儿智力、促进其语言发展的重要途径,对培养幼儿的认知、习惯、性格等有着极其重要的意义。

线性扫频激光器实时动态相频噪声特性研究

基于120°相差干涉和光场相位实时重构的窄线宽激光动态噪声特性测试方法,从时域频率调谐函数、频域频率噪声功率谱密度及其随时间的演化特征等方面,研究线性扫频激光器在不同扫频方式下动态相频噪声的细节特性。实验结果表明,扫频机理或参数差异导致结果呈现完全不同的实时动态噪声特性。电光调制能够在反馈锁相环辅助下获得最佳的扫频线性度,但会引起反馈谐振峰等噪声恶化,其控制参数不同,反馈谐振峰频率等特征也会发生变化;声光调制呈现最小程度的噪声恶化;压电调谐扫频线性度较差,且会附加较大的调谐噪声。该结果为激光器扫频机制及控制技术的研究和工程应用光源选型提供了参考。

光纤延迟环型射频存储技术的优化研究

光纤延迟环型射频存储技术因其大瞬时带宽、快速响应能力等优势在电子干扰领域备受关注。为了实现复杂脉冲信号的多样式存储,先后实现了移频型、门控半导体光放大器(SOA)型、级联型等不同光纤延迟环结构,通过对延迟环结构的对比分析和优化设计,获得了高保真、高分辨率、长时延、脉宽可重构的多功能存储方案。级联存储结构,实现了超过2000次脉冲复制、大于500μs的高分辨率长时延存储,以及200 ns^10μs的脉宽重构,可广泛应用于大范围脉宽、快速长时延存储和复杂调制格式等不同场景中。