Author Affiliations
Abstract
1 Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi’an Jiaotong University, Xi’an 710049, China
2 Solid-State Lighting Engineering Research Center, Xi’an Jiaotong University, Xi’an 710049, China
3 Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
4 HKUST LED-FPD Technology R&D Center at Foshan, Foshan 528200, China
Modulation bandwidth and the emission region are essential features for the widespread use of visible light communications (VLC). This paper addresses the contradictory requirements to achieve broadband and proposes ultrafast, asymmetric pyramids grown on adjacent deep concave holes via lateral overgrowth. Multicolor emission with an emission region between 420 nm and 600 nm is obtained by controlling the growth rate at different positions on the same face, which also can provide multiple subcarrier frequency points for the employment of wavelength division multiplexing technology. The spontaneous emission rate distinction is narrowed by lowering the number of the crystal plane, ensuring a high modulation bandwidth over broadband. More importantly, the residual stress and dislocation density were minimized by employing a patterned substrate, and lateral overgrowth resulted in a further enhancement of the recombination rate. Finally, the total modulation bandwidth of multiple subcarriers of the asymmetric pyramids is beyond GHz. These ultrafast, multicolor microLEDs are viable for application in VLC systems and may also enable applications for intelligent lighting and display.
Photonics Research
2021, 9(4): 04000452
Author Affiliations
Abstract
1 Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi’an Jiaotong University, Xi’an 710049, China
2 Solid-State Lighting Engineering Research Center, Xi’an Jiaotong University, Xi’an 710049, China
3 e-mail: yufengli@mail.xjtu.edu.cn
4 e-mail: fyun2010@mail.xjtu.edu.cn
Multimode and random directionalities are major issues restricting the application of whispering gallery mode microcavity lasers. We demonstrated a 40 μm diameter microring with an off-centered embedded hole and warped geometry from strained III-nitride quantum well multilayers. Single-mode directional whispering gallery mode lasing was achieved by the warped structure and high-order mode suppression induced by the off-centered hole. In addition, the introduction of the off-centered hole reduced the lasing threshold from 3.24 to compared with the warped microdisk without an embedded hole while maintaining a high-quality factor of more than 4000. Directional light emission in 3D was achieved and attributed to the warped structure, which provides a vertical component of the light emission, making it promising for building multifunctional coherent light sources in optoelectronic integration.
Photonics Research
2021, 9(4): 04000432
1 沈阳航空航天大学 电子信息工程学院，辽宁 沈阳 110122
2 中国科学院 沈阳自动化研究所，辽宁 沈阳 110000
针对近场目标高分辨力成像，基于220~325 GHz频段的近场雷达收发模块，在相同测量条件下，分别采用合成孔径雷达成像以及焦平面成像。对比合成孔径成像算法以及焦平面测量法的优劣，获得详细的测量参数以及成像效果对比，用于太赫兹近场成像分辨力的提高。
太赫兹 近场雷达 合成孔径雷达 焦平面 terahertz near field radar Synthetic Aperture Radar focal plane 太赫兹科学与电子信息学报
2020, 18(6): 962
Author Affiliations
Abstract
1 Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi’an Jiaotong University, Xi’an 710049, China
2 Solid-State Lighting Engineering Research Center, Xi’an Jiaotong University, Xi’an 710049, China
A full structure 290-nm ultraviolet light-emitting diode (UV-LED) with a nanoporous n-AlGaN underlayer was fabricated by top via hole formation followed by high-voltage electrochemical etching. The 20 to 120 nm nanopores were prepared in regular doped n-AlGaN by adjusting the etching voltage. The comparison between the Raman spectrum and the photoluminescence wavelength shows that the biaxial stress in the nanoporous material is obviously relaxed. The photoluminescence enhancement was found to be highly dependent on the size of the pores. It not only improves the extraction efficiency of top-emitting transverse-electric (TE)-mode photons but also greatly improves the efficiency of side-emitting transverse-magnetic (TM)-mode photons. This leads to the polarization change of the side-emitting light from to . The intensity of the electroluminescence was increased by 36.5% at 100 mA, and the efficiency droop at high current was found to decrease from 61% to 31%.
Photonics Research
2020, 8(6): 06000806
1 沈阳航空航天大学，电子信息工程学院，沈阳 110136
2 辽宁省通用航空重点实验室，沈阳 110136
针对传统的ADS-B报文软件解析过程较为复杂、不易理解的问题, 提出一种逻辑简单、易于实现的解析方法。首先, 将网口接收的16进制报文数据转换成相应的01字符串。根据ADS-B报文的结构进行CPR算法的程序实现。最后, 通过SBS-3设备网络端口实时发送ADS-B报文数据, 利用Qt平台实现对ADS-B报文数据的接收和解析工作。通过实际测试并与传统方法对比, 结果表明: 研究的方法和设计的解析程序可以对ADS-B报文数据进行实时解析, 其结果与SBS-3设备提供的硬件参考结果相同, 实验验证了所提方法的有效性与可行性。
广播式自动相关监视 1090ES数据链 报文解析 CPR算法 Qt平台 ADS -B 1090ES data link message parsing CPR algorithm Qt platform
Author Affiliations
Abstract
1 College of Engineering, China Agricultural University Beijing 100083, P. R. China
2 College of Mechanical and Electrical Engineering Zhongkai University of Agriculture Engineering Guangzhou 510225, P. R. China
3 Crop Genetics and Breeding Research Unit USDA-ARS, 2747 Davis Road, Tifton, GA 31793, USA
4 College of Food Science & Nutritional Engineering China Agricultural University, Beijing 100083, P, R. China
5 Quality & Safety Assessment Research Unit U.S. National Poultry Research Center, USDA-ARS 950 College Station Rd., Athens, GA 30605, USA
6 Quality & Safety Assessment Research Unit USDA-ARS, Athens, GA 30605, USA
7 Institute of Food Science and Technology Jiangsu Academy of Agricultural Sciences Nanjing 210014, P. R. China
8 Multidisciplinary Initiative Center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049, P. R. China
9 Lingang Experimental Middle School Linyi 276624, P. R. China
The growth characteristics of Aspergillus parasiticus incubated on two culture media were examined using shortwave infrared (SWIR, 1000–2500 nm) hyperspectral imaging (HSI) in this work. HSI images of the A. parasiticus colonies growing on rose bengal medium (RBM) and maize agar medium (MAM) were recorded daily for 6 days. The growth phases of A. parasiticus were indicated through the pixel number and average spectra of colonies. On score plot of the first principal component (PC1 T and PC2, four growth zones with varying mycelium densities were identified. Eight characteristic wavelengths (1095, 1145, 1195, 1279, 1442, 1655, 1834 and 1929 nm) were selected from PC1 loading, average spectra of each colony as well as each growth zone. Furthermore, support vector machine (SVM) classifier based on the eight wavelengths was built, and the classification accuracies for the four zones (from outer to inner zones) on the colonies on RBM were 99.77%, 99.35%, 99.75% and 99.60% and 99.77%, 99.39%, 99.31% and 98.22% for colonies on MAM. In addition, a new score plot of PC2 and PC3 was used to differentiate the colonies incubated on RBM and MAM for 6 days. Then characteristic wavelengths of 1067, 1195, 1279, 1369, 1459, 1694, 1834 and 1929 nm were selected from the loading of PC2 and PC3. Based on them, a new SVM model was developed to differentiate colonies on RBM and MAM with accuracy of 100.00% and 99.99%, respectively. In conclusion, SWIR hyperspectral image is a powerful tool for evaluation of growth characteristics of A. parasiticus incubated in different culture media.
Aspergillus parasiticus growth characteristics characteristic wavelengths shortwave infrared (SWIR) hyperspectral imaging Journal of Innovative Optical Health Sciences
2018, 11(5): 1850031
Author Affiliations
Abstract
National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001
The lasing characteristics of composite Tm:YAG rod with undoped ends at room temperature are reported. The maximum output power at 2.015 \mum is 6.97 W and the slope efficiency is 41.45%. Focusing point and output coupler are changed to find the optimization condition. The relationship between operation temperature and output power is discussed. Comparison between Tm:YAG and composite Tm:YAG testifies the superiority of composite crystal.
二极管泵浦 复合Tm:YAG晶体 室温 140.3070 Infrared and far-infrared lasers 140.3580 Lasers, solid-state 140.3480 Lasers, diode-pumped Chinese Optics Letters
2008, 6(8): 594
Author Affiliations
Abstract
1 National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001
2 Laser and Optoelectronic Functional Material R and D Center, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
We report a continuous-wave (CW) 2.1-\mum Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-\mum Tm:YAP laser. The maximum output power of 1.5 W is obtained from Ho:YAG laser, corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-Ho conversion efficiency of 5.6%.
Tm:YAP Ho:YAG 二极管泵浦 谐振泵浦 140.3580 Lasers, solid-state 140.5680 Rare earth and transition metal solid-state lasers 140.3480 Lasers, diode-pumped 140.3070 Infrared and far-infrared lasers Chinese Optics Letters
2008, 6(7): 520
Author Affiliations
Abstract
National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001
The lasing characteristics of Tm:LuAG at room temperature are reported. The maximum output power at 2.023-\mum wavelength is 4.91 W and the slope efficiency is 25.39%. The mode matching between pump mode and laser mode is optimized by changing the pump beam waist radius and its location. Different output couplers are used to realize the optimal laser output. The relationship between operation temperature and output power is also discussed.
二极管泵浦 Tm:LuAG晶体 室温 140.3070 Infrared and far-infrared lasers 140.3480 Lasers, diode-pumped 140.3580 Lasers, solid-state Chinese Optics Letters
2008, 6(6): 415
哈尔滨工业大学可调谐激光技术国家级重点实验室, 黑龙江 哈尔滨 150001
为了获得高效率、小型化、稳定性好的激光器,种子激光器由激光二极管抽运Tm,Ho:YLF微片获得单模输出。短腔的自由光谱区比较宽,易于选单纵模,微片厚度0.9 mm,两端镀膜,构成微型谐振腔。微片置于杜瓦瓶中,采用液氮制冷的方式,在低温下工作,增加了输出激光的稳定性。利用光纤延时自拍法进行频率短期稳定度测量,得到单模激光器短期稳定度为2.6 kHz/μs,利用示波器估测长期稳定度小于35 MHz。获得2.067 μm的单模输出,线宽小于40 MHz。利用刀口法测量得到光束质量为1.082,最大单模输出功率为32.8 mW,斜率效率达到25.2%,光-光转换效率达23.8%,功率输出不稳定性小于1%。
激光器 红外固体激光器 激光二极管抽运 Ho:YLF晶体 单纵模
