浙江大学 信息与电子工程学院, 杭州 310027
为了实现大规模2维相控阵天线的光学真时延系统, 采用基于硅基光子学的二进制硅基集成二进制光延迟线技术, 提出一种2维相控阵(N×N)真时延网络, 利用2维相控阵结构的对称性以及行延迟和列延迟的独立控制, 真时延网络的复杂度可以降低至(N-1)/2(N为奇数)或N/2(N为偶数)。理论分析了该时延控制方案和集成时延芯片的设计,以8×8的2维相控阵为例, 设计实现了包含4种硅基二进制时延线的真时延芯片, 测量了该芯片的时延量, 并针对测量的时延量仿真分析了2维相控阵天线的波束扫描特性。结果表明, 该真时延网络能够满足相控阵天线波束指向要求(角度误差小于0.5°);集成光学技术的采用减小系统的体积和成本。该研究为大规模2维相控阵天线的真时延网络实现提供了一种可行的方法。
集成光学 光学真时延 二进制时延线 相控阵天线 integrated optics optical true time-delay binary time-delay line phased array antenna
浙江大学 信息与电子工程学院, 杭州 310027
为了提升光载射频传输链路的链路增益以及传输距离, 采用了L波段的超长分布式2阶喇曼放大器结构对光信号进行放大。从理论上对分布式2阶喇曼放大器以及光载射频传输链路的原理进行了解释, 利用信号光、1阶抽运光、2阶抽运光以及噪声之间的耦合方程组分析了它们之间的关系, 并且得到了基于超长分布式2阶喇曼放大器的光载射频传输系统的1阶射频信号增益。通过数值仿真以及系统实验得到了抽运功率大小对超长分布式2阶喇曼放大器的开关增益的影响、光载射频传输系统在0GHz~7GHz范围内的频率响应及其射频增益以及该光载射频传输链路在应用超长分布式2阶喇曼放大器后的相位噪声情况。结果表明, 光载射频传输在超长分布式2阶喇曼放大器的作用下获得了28.1dB的链路增益, 在距离为80.94km的光链路上实现了近似无损传输, 射频信号开关增益与射频信号频率无关。该研究在光载射频链路的长距离传输中有重要的应用价值。
光纤放大器 光载射频传输 超长分布式2阶喇曼放大器 光纤色散 相位噪声 fiber amplifier radio-over-fiber transmission ultra-long distributed 2-order Raman amplifier fiber dispersion phase noise
Author Affiliations
Abstract
College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China
Electromagnetic vortices, which describe the orbital angular momentum (OAM) carrying waves with a helical phase front, have recently attracted much interest in a radio frequency domain due to their potential applications in many diverse areas. In an OAM-based scenario, the antenna for OAM mode multiplexing/demultiplexing plays an essential role in controlling the overall system performance. In this paper, we demonstrated theoretically and experimentally an easily realized OAM antenna based on the traveling-wave circular loop structure for efficiently multiplexing/demultiplexing multiple OAM modes; in addition, its general propagation characteristics including the polarization, divergence, and radiation pattern are mathematically analyzed. Schemes for antenna size reduction and various radiation pattern manipulations have also been discussed to realize a more flexible and compact system.
Optical vortices Optical vortices Wave-front sensing Wave-front sensing Electromagnetic optics Electromagnetic optics Microwaves Microwaves Photonics Research
2016, 4(5): 050000B9
Author Affiliations
Abstract
Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
Spurious-free dynamic range (SFDR) limited by intermodulation distortions is a usually accepted measure for dynamic performance of a photonic time-stretched analog-to-digital converter (ADC). In this paper, SFDR improvement in a photonic time-stretched ADC based on third-order predistortion is proposed. The third-order predistortion is achieved optically within an integrated dual-parallel Mach–Zehnder modulator (DPMZM). The mechanism of SFDR improvement with third-order predistortion in the DPMZM is theoretically analyzed. Compared with a conventional scheme without predistortion, the experimental results show that the SFDR improvement of ～26 dB in the proposed scheme is proved.
Fiber optics links and subsystems Nonlinear optical signal processing Data processing by optical means Photonics Research
2014, 2(5): 05000097
浙江大学信息与电子工程系, 浙江 杭州 310027
提出了一种基于双通道马赫曾德尔调制器(DPMZM)调制边带滤波的微波光子移相器。在双通道马赫曾德尔调制器的结构中，在一路马赫曾德尔干涉仪上实现抑制光载波的双边带调制输出，而在另一路马赫曾德尔的相位调节臂上通过调节偏置电压实现光载波信号的光学移相，两路光信号经过干涉合路后由光纤布拉格光栅(FBG)滤除其中一个一阶边带，最后输入到光电探测器(PD)进行光电转换得到移相的微波信号。实验结果表明，基于DPMZM调制边带滤波的微波光子移相器具有传输特性稳定、输出幅度波动小的优点。该结构还具有相移调节响应速度快、应用频带宽以及移相范围大于360°等特点。
光纤光学 光纤光栅 微波光子移相器 双通道马赫曾德尔调制器 马赫曾德尔干涉仪 光学学报
2012, 32(12): 1223003
Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
Frontiers of Optoelectronics
2011, 4(3): 277
Author Affiliations
Abstract
1 Department of Information and Electronic Engineering, Zhejiang University, Hangzhou 310027
2 Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080
A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.
060.2370 fiber optics sensors 350.2770 gratings 160.6060 solgel 160.5470 polymers Chinese Optics Letters
2004, 2(12): 12683
