清华大学 电子工程系/北京国家信息科学技术研究中心， 北京 100084
随着射频通信频谱资源的逐渐饱和，局域范围内高速通信亟需开辟一条新的赛道，而可见光通信得益于光的大带宽本质和通信范围有限而频谱免许可，是传统通信的理想补充之一。GaN基蓝绿光发光光源近十年来的快速发展，特别是性能优良的小尺寸高速光源microLED的发展，使其成为“万物互联”的物联网时代终末端通信的重要促进力量。文章分蓝绿光microLED和带有谐振腔的GaN基蓝绿光光源(含超辐射发光二极管和激光器)两个主要类别，回顾了蓝绿光高速光源的发展历程和最新进展，主要包括microLED结构与阵列、面发射腔增强光源、边发射腔增强光源三个方面。
光通信 氮化镓 高速 谐振腔 optical communication gallium nitride highspeed microLED microLED resonator
红外与激光工程
2022, 51(5): 20220270
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
超宽带光电子芯片是下一代无线通信、先进电子信息装备中光纤传输与信号处理的关键元器件, 芯片中光子、电子、电磁场之间的相互作用是决定芯片性能的核心因素。文章通过介绍超宽带光电探测器芯片、电光调制器芯片等方面的研究进展, 分享课题组在破解上述核心科学问题、提高芯片性能的关键技术方案。
光电子芯片 光探测器 电光调制器 optoelectronic devices photodetectors optical modulators
红外与激光工程
2021, 50(7): 20211052
Author Affiliations
Abstract
Beijing National Research Center for Information Science and Technology (BNRist), Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
A novel thin-film lithium niobate (TFLN) electro-optic modulator is proposed and demonstrated. -silica hybrid waveguide is adopted to maintain low optical loss for an electrode spacing as narrow as 3 µm, resulting in a low half-wave-voltage length product of only 1.7 V·cm. Capacitively loaded traveling-wave electrodes are employed to reduce the microwave loss, while a quartz substrate is used in place of a silicon substrate to achieve velocity matching. The fabricated TFLN modulator with a 5-mm-long modulation region exhibits a half-wave voltage of 3.4 V and a merely less than 2 dB roll-off in an electro-optic response up to 67 GHz.
lithium niobate electro-optic modulator wideband half-wave voltage Chinese Optics Letters
2021, 19(6): 060016
清华大学电子工程系，北京国家信息科学技术研究中心，北京 100084
目前，c面氮化镓(GaN)基发光二极管的制备技术已经十分成熟并取得了商业化成功，但仍面临极化电场导致的大电流密度下效率下降(Droop效应)和黄绿光波段效率低的问题。为消除极化电场的影响，人们开始关注半极性和非极性面GaN。其中，基于传统极性面衬底通过三维结构生长来获得半极性和非极性GaN的方法，由于其低成本和生长的灵活性，受到了广泛研究。本文首先总结了三种GaN三维结构的制备方法并分析其生长机理。接着，在此基础上介绍了不同晶面InGaN量子阱的外延生长和发光特性。最后，列举了GaN基三维结构在半极性面LED、颜色可调LED和无荧光粉白光发光二极管方面的应用。
氮化镓 发光二极管 三维结构 无荧光粉白光 效率下降 GaN lightemitting diode threedimensional structure phosphorfree white light efficiency droop
Author Affiliations
Abstract
1 Beijing National Research Center for Information Science and Technology (BNRist), Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
2 Center for Flexible Electronics Technology, Tsinghua University, Beijing 100084, China
3 Flexible Intelligent Optoelectronic Device and Technology Center, Institute of Flexible Electronics Technology of THU, Jiaxing 314006, China
An equivalent circuit model including multi-section distributed parameters is proposed to analyze wideband photodiodes (PDs) with coplanar waveguide (CPW) electrodes. The model helps extract CPW parameters as well as intrinsic bandwidth parameters so that the influence of the CPW structure can be investigated, making it valuable for the design of high-performance PDs. PDs with an inductive 115 Ω impedance CPW are fabricated, and the 3 dB bandwidth is improved from 28 GHz to 37.5 GHz compared with PDs with a conventional 50 Ω impedance CPW.
photodiodes photodetector high-impedance coplanar waveguide Chinese Optics Letters
2020, 18(6): 061301
清华大学 电子工程系 清华信息科学与技术国家实验室(筹), 北京 100084
提出了一种基于朗伯型反射面的LED间接照明系统, 即LED光源出射的光全部通过朗伯型反射面反射后再照射目标区域, 该系统具有光源亮度均匀、灯具效率高等优点, 很好地解决了高亮度LED点光源给室内照明带来的眩光问题。首先提出了一种能够很好逼近朗伯反射面的复合型微结构表面, 并通过Lighttools光学仿真对其分布参数进行了优化, 使最终结果在不同光线入射角的情况下, 都具有较理想的余弦反射特性。在此基础上, 设计了整体光学系统, 使其实现了近180°范围的角度亮度的均匀性和高达84.7%的灯具效率, 验证了间接照明方法的可行性。
室内照明 朗伯型反射面 微结构 光学仿真 LED LED indoor illumination Lambert reflection surface micro-structure optical simulation
Tsinghua National Lab on Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
A simple method is proposed to design freeform surface for Lambertian extended source. In this method, it can take advantage of the designing method for point source via substituting each incident ray with a dynamically calculated equivalent ray. For each facet on the freeform surface, the equivalent ray emits from the energy weighted average-emitting-position for the corresponding incident beam, and redirects into the direction which is determined by a source-to-target mapping. The results of the designing examples show that the light distributions’ uniformities can be improved by this method, e.g., even the improvement of 59% can be achieved.
nonimaging optics nonimaging optics illumination design illumination design light emitting diodes (LEDs) light emitting diodes (LEDs) Frontiers of Optoelectronics
2016, 9(2): 330
Tsinghua National Laboratory for Information Science and Technology/State Key Lab of Integrated Optoelectronics,Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
Laser annealing of silicon dioxide (SiO2) film formed by inductively coupled plasma enhanced chemical vapor deposition (ICPECVD) is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO2 film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO2 film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO2 film can be significantly improved by laser annealing. Al2O3/SiO2 waveguide has been fabricated on silicon substrate with the SiO2 lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.
laser annealing laser annealing waveguide loss waveguide loss silicon dioxide silicon dioxide inductively coupled plasma enhanced chemical vapor inductively coupled plasma enhanced chemical vapor Frontiers of Optoelectronics
2016, 9(2): 323
