Author Affiliations
Abstract
Beijing National Research Center for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach–Zehnder modulator and an additional asymmetry Mach–Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of at an signal-to-noise ratio (SNR) of 9.6 dB. When the SNR is -10.4 dB, the AOA error is , and the chirp rate, measured as , has a standard deviation of . The measured chirp rate agrees well with the real LFM signal.
microwave photonics interferometer angle of arrival linear frequency modulation Chinese Optics Letters
2020, 18(12): 123902
1 南京航空航天大学机械结构力学及控制国家重点实验室, 江苏 南京 210016
2 中航工业集团公司北京航空制造工程研究所, 北京 100024
基于光纤布拉格光栅和傅里叶热传导方程提出了一种实现复合材料圆筒结构热扩散系数测量的水热平衡法，并进行了理论分析和实验研究。当圆筒结构内部流体温度升高，由初始低温平衡状态向高温平衡状态过渡，其内部流体热量从内向外传递，由于热阻的存在，而使内外壁呈现不同的温度特性，导致内外壁温度分布呈现差异性；依此原理，利用光纤布拉格光栅温度敏感特性，获取中心波长与温度函数关系及中心波长与时间函数关系，确定圆筒结构温度分布函数；根据傅里叶一维导热方程和边界条件即可求得结构热扩散系数。实验表明，升温测量与降温测量结果具有一致性，证明了该测量方案的可行性与可靠性。该测量系统具有传感元件简单、稳定性好、可操作性强等优点，为此类圆筒结构热扩散系数测量提供了一种新颖可行的方法。
测量 热扩散系数 水热平衡法 碳纤维复合材料 光纤布拉格光栅 中国激光
2013, 40(11): 1108001
