1 广西大学 计算机与电子信息学院，南宁530004
2 清华大学 电子工程系，北京100084
3 广西多媒体通信与网络技术重点实验室，南宁530004
为减少目前微波光子领域到达角（AOA）测量易受相位、噪声等影响，实现二维平面内大范围的AOA测量，提出并实验验证了一种基于微波光子去斜接收的二维AOA估计方案。该方案接收端利用L型天线阵加入固定延迟时间的方法，可以估计一维AOA，利用该一维AOA可求解出二维AOA（俯仰角和方位角）。实验结果表明：在天线间隔为5 m，输入线性调频连续信号的信噪比为10 dB或-7.8 dB的情况下，所提方案的一维AOA的估计结果具有大范围的特点，且在-79°~74°内估计误差均小于2°，同时，计算得到的俯仰角和方位角在较大范围内都具有较高的精度。
微波光子学 去斜 二维到达角 线性调频信号 microwave photonics, de-chirping reception, two-di
1 广西大学计算机与电子信息学院，广西 南宁 530004
2 清华大学电子工程系北京信息科学与技术国家研究中心，北京 100084
提出了一种基于相干接收机的相干光谱分析方案。采用相干接收机将待测信号与本振光进行同相和正交（IQ）混频和平衡探测，依据光外差原理计算出待测信号的功率，根据所计算出的功率与相应的本振频率之间的映射关系对待测信号的光谱进行重构。实验结果表明，当本振的扫描速率在80~200 nm/s范围时，分辨率优于12.5 MHz。所提出的光谱分析方案具备超高分辨率，可用于快速提取超密集波分复用系统精细的光谱结构。
光谱学 光外差 相干接收机 超密集波分复用 超高分辨率 激光与光电子学进展
2023, 60(19): 1930001
1 广西大学 计算机与电子信息学院, 南宁 530004
2 清华大学 电子工程系, 北京 100084
为了实现多通道的微波光子下变频, 提高变频链路性能, 提出一种使用单个集成调制器实现的微波光子下变频方案, 该方案利用偏振复用特性实现双通道下变频功能。仿真与实验结果表明: 当子调制器设置在最小传输点时, 可实现载波抑制双边带调制, 光载波抑制比达到29 dB；双通道分别独立地将射频信号下变频转换为中频信号, 杂散抑制比达30 dB左右, 2个通道的无杂散动态范围(SFDR)分别达到110.4 dB·Hz2/3、113.4 dB·Hz2/3。
微波光子 光通信 下变频 双偏振双平行马赫-曾德尔调制器 双通道变频系统 microwave photonic, optical communication, down-co
1 广西大学计算机与电子信息学院，广西 南宁 530004
2 清华大学电子工程系北京信息科学与技术国家研究中心，北京 100084
为了提高微波光子链路在宽带传输的无杂散动态范围（SFDR），提出了一种单驱动双平行马赫-曾德尔调制器（SD-DPMZM）的宽带线性化方案。该方案通过使用一个180°混合耦合器和调整调制器的偏置点，在理论上完全消除三阶交调失真（IMD3）。输入双音信号进行仿真，实验结果表明该方案能完全消除IMD3，当以10 GHz和10.01 GHz为双音信号输入时，IMD3抑制达68 dB，SFDR比传统型提高14.5 dB。此外，信号从X波段变化到K波段时，SFDR可始终保持在114.3 dB·Hz2/3以上。
调制器 微波光子链路 三阶交调失真 无杂散动态范围 激光与光电子学进展
2022, 59(17): 1713002
清华大学电子工程系北京信息科学与技术国家研究中心, 北京 100084
高频宽带分布相参微波光子成像雷达具有速度分辨率高、距离分辨率高、角度分辨率高、信噪比高等优点,是高精度成像雷达的一个发展方向。其核心功能模块包括:微波光子信号产生、光学分数域接收前端及高精度光纤时频同步环网。对上述三个关键模块的国内外发展现状进行了简要回顾,重点介绍了我国在国家自然科学基金重大项目支持下,在动态可重构波形产生、光学分数域接收前端、高精度时频同步环网等方面取得的成果,以及基于这些成果搭建的基于微波光子学原理的X波段分布相参宽带成像雷达实验系统以及阶段性的实验结果。
中国激光
2021, 48(15): 1517003
1 烽火通信科技股份有限公司, 武汉 430074
2 锐光信通科技有限公司, 武汉 430074
3 清华大学 电气工程系, 北京 100084
为支持光子轨道角动量(OAM)模式大容量通信传输, 文章探讨了新型OAM信号传输光纤的设计与制备技术, 满足大幅度提高通信系统频谱效率和容量对特殊光纤的需求。文章模拟和评估了OAM模式在不同波导结构光纤中的模式特性和传播效果, 研究结果表明, 提高芯—包层折射率差有利于高阶OAM模式传输, 降低了光纤内部的各种微扰。采用等离子体化学气相沉积工艺, 高精度实现了设计的折射率剖面, 并成功拉制了高质量的OAM光纤, 其支持50 km传输28个有效OAM通道的渐变折射率; 开发出了可支持96个有效OAM通道的三环芯层结构传输光纤。同时, 针对新型传输需求, 通过对精确制备技术进行模拟, 研究开发出了保偏型OAM传输光纤和OAM掺铒光纤等支持更多OAM模式稳定传输的新型光纤。
轨道角动量 渐变环形光纤 三环形光纤 保偏型轨道角动量光纤 OAM gradient ring fiber three ring fiber polarization-maintaining OAM fibers
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
Author Affiliations
Abstract
Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
A broadband photonic analog-to-digital converter (ADC) for X-band radar applications is proposed and experimentally demonstrated. An X-band signal with arbitrary waveform and a bandwidth up to 2 GHz can be synchronously sampled and processed due to the optical sampling structure. In the experiment, the chirp signal centered at 9 GHz with a bandwidth of 1.6 GHz is sampled and down-converted with a signal-to-noise ratio of 7.20 dB and an improved noise figure. Adopting the photonic ADC in the radar receiver and the above signal as the transmitted radar signal, an X-band inverse synthetic aperture radar system is set up, and the range and cross-range resolutions of 9.4 and 8.3 cm are obtained, respectively.
060.5625 Radio frequency photonics Chinese Optics Letters
2018, 16(6): 060605
Author Affiliations
Abstract
1 Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
2 FiberHome Telecommunication Technologies Co., Ltd., Wuhan 430074, China
We present the investigation on deformation of orbital angular momentum (OAM) modes in bending ring-core fibers (RCFs) with different structure sizes through numerical and experimental studies. The effective refractive index differences of even and odd fiber eigenmodes, which constitute OAM±1,1 modes, induced by RCF bending and their impacts on the OAM±1,1 mode intensity distributions are analyzed. Bending experiments are also carried out on three different RCFs, and the results match well with simulation values. It is found that RCFs with smaller inner and outer radii show preferable tolerance to the fiber bending.
050.4865 Optical vortices 060.2270 Fiber characterization 060.2310 Fiber optics Chinese Optics Letters
2017, 15(3): 030501
Author Affiliations
Abstract
Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
A highly linear W-band receiver front-end based on higher-order optical sideband (OSB) processing is proposed and experimentally demonstrated. Two-tone analysis shows that by manipulating higher-order OSBs, the third-order intermodulation distortion (IMD3) introduced by optoelectronic components (mainly modulators) in the receiver front-end can be further suppressed, and a 9 dB improvement of the ratio of the fundamental and IMD3 can be attained. In the experiment, the spurious-free dynamic range of the W-band receiver front-end is up to 122.1 dB·Hz2/3, with improvement by 9 dB compared with that of only processing the five OSBs.
060.2360 Fiber optics links and subsystems 060.5625 Radio frequency photonics 130.4310 Nonlinear Chinese Optics Letters
2017, 15(5): 050603
