Author Affiliations
Abstract
1 Nanjing University, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, School of Physics, National Laboratory of Solid State Microstructures, Nanjing, China
2 Beijing Academy of Quantum Information Sciences, Beijing, China
3 Xin Lian Technology Co., Ltd., Huzhou, China
Free-space optical communication (FSO) can achieve fast, secure, and license-free communication without physical cables, providing a cost-effective, energy-efficient, and flexible solution when fiber connection is unavailable. To achieve FSO on demand, portable FSO devices are essential for flexible and fast deployment, where the key is achieving compact structure and plug-and-play operation. Here, we develop a miniaturized FSO system and realize 9.16 Gbps FSO in a 1 km link, using commercial single-mode-fiber-coupled optical transceiver modules without optical amplification. Fully automatic four-stage acquisition, pointing, and tracking systems are developed, which control the tracking error within 3 μrad, resulting in an average link loss of 13.7 dB. It is the key for removing optical amplification; hence FSO is achieved with direct use of commercial transceiver modules in a bidirectional way. Each FSO device is within an overall size of 45 cm × 40 cm × 35 cm, and 9.5 kg weight, with power consumption of ∼10 W. The optical link up to 4 km is tested with average loss of 18 dB, limited by the foggy test environment. With better weather conditions and optical amplification, longer FSO can be expected. Such a portable and automatic FSO system will produce massive applications of field-deployable high-speed wireless communication in the future.
free-space optical communication acquisition, pointing, and tracking system field-deployable system Advanced Photonics Nexus
2023, 2(6): 065001
1 河北工业大学电子信息工程学院，天津 300401
2 山东省烯烃催化与聚合重点实验室，山东 滨州 256500
3 河北工业大学科学技术研究院，天津 300401
受激拉曼散射（SRS）脉宽压缩技术由于其高负载、高压缩率、相位共轭等特性，在高功率短脉冲激光产生方面有着重要应用。本文从SRS压缩机理、增益介质、压缩结构等方面对SRS脉宽压缩技术的研究进展进行了分析和综述。
激光光学 受激拉曼散射 脉冲压缩 短脉冲产生 激光与光电子学进展
2023, 60(17): 1700008
Hua-Ying Liu 1,2,3,*†Minghao Shang 1,2,3Xiaoyi Liu 1,3,4Ying Wei 1,2,3[ ... ]Shining Zhu 1,2,3,5
Author Affiliations
Abstract
1 Nanjing University, National Laboratory of Solid State Microstructures, Nanjing, China
2 Nanjing University, School of Physics, Nanjing, China
3 Nanjing University, Collaborative Innovation Center of Advanced Microstructures, Nanjing, China
4 Nanjing University, School of Electronic Science and Engineering, Nanjing, China
5 Nanjing University, College of Engineering and Applied Sciences, Nanjing, China
The large-photon-number quantum state is a fundamental but nonresolved request for practical quantum information applications. We propose an N-photon state generation scheme that is feasible and scalable, using lithium niobate on insulator circuits. Such a scheme is based on the integration of a common building block called photon-number doubling unit (PDU) for deterministic single-photon parametric downconversion and upconversion. The PDU relies on a 107-optical-quality-factor resonator and mW-level on-chip power, which is within the current fabrication and experimental limits. N-photon state generation schemes, with cluster and Greenberger–Horne–Zeilinger state as examples, are shown for different quantum tasks.
deterministic parametric downconversion multiphoton generation lithium niobate on isolator microring resonator deterministic parametric upconversion Advanced Photonics Nexus
2023, 2(1): 016003
1 中国科学院 声学研究所东海研究站, 上海 201815
2 华东师范大学 软件工程学院 国家可信嵌入式软件工程技术研究中心, 上海 200062
低强度聚焦超声治疗技术是当前超声治疗领域的研究热点, 应用场景不同对于超声系统的参数和性能要求也具有差异化, 相控阵技术的引入为解决聚焦声场精确控制带来了新的思路。现有相控阵聚焦超声控制系统的输出参数相对固定, 频率和功率可调范围窄, 且支持换能器阵列通道的规模较小。该文设计了一种基于现场可编程逻辑门阵列(FPGA)的256通道的相控阵超声控制系统。实验结果表明, 该系统实现频率1~3 MHz 可调, 输出电压峰-峰值±100 V连续可调, 相位延时精度为5 ns, 可驱动不同阵元数的相控阵探头, 从而为超声治疗技术的研究提供多元化激励实施方案。
256通道 低强度聚焦超声 超声控制系统 相控阵 超声治疗 256 channels low intensity focused ultrasound ultrasound control system phased array ultrasound therapy
1 西安邮电大学计算机学院，陕西 西安 710121
2 西安邮电大学陕西省网络数据分析与智能处理重点实验室， 陕西 西安 710121
3 空军工程大学信息与导航学院，陕西 西安 710077
根据目标检测算法中出现的目标漏检和重复检测问题，本文提出了一种基于双阈值-非极大值抑制的Faster R-CNN改进算法。算法首先利用深层卷积网络架构提取目标的多层卷积特征，然后通过提出的双阈值-非极大值抑制(DT-NMS)算法在RPN阶段提取目标候选区域的深层信息，最后使用了双线性插值方法来改进原RoI pooling层中的最近邻插值法，使算法在检测数据集上对目标的定位更加准确。实验结果表明，DT-NMS算法既有效地平衡了单阈值算法对目标漏检问题和目标误检问题的关系，又针对性地减小了同一目标被多次检测的概率。与soft-NMS算法相比，本文算法在PASCAL VOC2007上的重复检测率降低了2.4%，多次检测的目标错分率降低了2%。与Faster R-CNN算法相比，本文算法在PASCAL VOC2007上检测精度达到74.7%，性能提升了1.5%。在MSCOCO数据集上性能提升了1.4%。同时本文算法具有较快的检测速度，达到16 FPS。
计算机视觉 目标检测 非极大值抑制 卷积神经网络 computer vision object detection non-maximum suppression convolutional neural network
Author Affiliations
Abstract
Key Laboratory of Optical Communication and Lightwave Technology, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876
The present paper proposes a novel design for achieving single-polarization single-mode (SPSM) operation at 1550 nm in photonic crystal fiber (PCF), using a rectangular-lattice PCF with two lines of three central air holes enlarged. The proposed PCF composed entirely of silica material is modeled by a full-vector finite element method with anisotropic perfectly matched layers. Simulations show that single-polarization operation within broad wavelength range can be easily realized with the proposed structure. The wide-band SPSM operation features, the low confinement losses, and the small effective mode area are the main advantages of the proposed PCF structure. A SPSM-PCF with confinement loss less than 0.1 dB/km within wavelength range from 1370 to 1610 nm and effective mode area about 4.7 micron2 at 1550 nm is numerically demonstrated.
光子晶体光纤 有限元方法 单偏振 限制损耗 060.2280 Fiber design and fabrication 060.2310 Fiber optics 060.2420 Fibers, polarization-maintaining 060.2430 Fibers, single-mode Chinese Optics Letters
2007, 5(5): 260
北京邮电大学光通信与光波技术教育部重点实验室，北京 100876
应用全矢量有限元方法，分析了椭圆形高折射率芯Bragg光纤的偏振和色散特性，详细讨论了光纤结构参量对模式双折射的影响，结果发现：椭圆形高折射率芯Bragg光纤的模式双折射在10－3量级，比传统保偏光纤高出一个量级，且随波长的增加而单调递增；模式双折射随包层低折射率材料填充比的增加而减小，但与包层周期的变化几乎无关．此外，提高椭圆率或材料间的折射率比可显著增强模式双折射．研究结果有助于设计高性能的一维微结构保偏光纤．
导波与光纤光学 Bragg光纤 有限元 偏振 色散 Guided wave and fiber optics Bragg fibers Finite element Polarization Dispersion
