1 天津大学精密仪器与光电子工程学院,天津 300072
2 珠海光库科技股份有限公司,广东 珠海 519080
基于薄膜铌酸锂干法刻蚀工艺不能获得高垂直度截面的特点,设计了一种基于折射率相近的填充材料作为模斑转换结构。所设计结构可兼容不同尺寸的输出光斑且整体结构的转换效率大于-0.28 dB。所提方案避免了薄膜铌酸锂干法刻蚀后的大倾角断面直接作为耦合端面时性能低的劣势,可提升薄膜铌酸锂电光调制器件在片上集成激光芯片的性能。三维模拟结果显示该结构对工艺误差不敏感、加工可行性高,为减小集成器件体积、降低成本及高密度集成提供可行方案。
薄膜 铌酸锂 片上集成 倒装焊 模斑转换 光学学报
2023, 43(23): 2331001
Author Affiliations
Abstract
1 Terahertz Technology Innovation Research Institute, Terahertz Spectrum and Imaging Technology Cooperative Innovation Center, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
2 Shanghai Institute of Intelligent Science and Technology, Tongji University, Shanghai 200092, China
Low-loss dielectric terahertz (THz) chips are efficient platforms for diverse THz applications. One of the key elements in the chip is the coupler. Most of the available THz couplers are in-plane and couple the THz wave from the metal waveguide to the dielectric waveguide. However, out-of-plane couplers are more suitable for wafer-scale testing and tolerant of alignment variation. In this work, we propose an out-of-plane THz coupler for coupling the antenna to the dielectric waveguide. The device is constructed using a grating and a compact spot-size converter. As the conventional optical spot-size converters that apply directly to THz chips are too large, we have designed a compact spot-size converter based on a tapered waveguide with a lens. The total device is 2.9 cm long and can couple a 7 mm diameter THz beam to a 500 µm wide waveguide. The device can scan the THz beam, radiate the input rectangular waveguide mode to free space, and drive the rotation angle of the fan beam through the scanning frequency. We fabricated the device using a single lithography step on a silicon wafer. The out-of-plane coupling efficiency was found to be ∼5 dB at 194 GHz. The fan-beam steering range was found to be around 40° in the frequency range of 170–220 GHz. The proposed out-of-plane coupling technique may provide an effective way for THz wafer-scale testing with a higher degree of freedom for on-chip integration. Also, the proposed technique being non-mechanical, beam steering using it, may therefore find applications in THz radar, communication, and sensing.
terahertz device grating coupler spot-size converter beam steering Chinese Optics Letters
2022, 20(2): 021301
山东大学信息科学与工程学院, 山东 青岛 266237
提出了一种新型的基于渐变折射率波导自聚焦效应的模斑变换器,分析了均匀折射率波导和渐变折射率波导的模式场分布及传输特性,研究了自聚焦效应的原理。利用时域有限差分法,计算得到了该变换器的插入损耗和回波损耗,所提模斑变换器与现有的最好模斑变换器的性能相当,但长度缩短至其1/6。该新型模斑变换器可用于集成光学系统中。
集成光学 硅基光电集成 模斑变换器 渐变折射率波导 自聚焦效应
清华大学 信息科学与技术国家实验室(筹), 北京 100084
半导体光调制器波导的输出模斑通常是直径为2~3μm的椭圆形, 与光纤进行耦合时会因模斑不匹配而产生严重的耦合损耗, 并影响对准容差。为降低光纤与调制器波导的耦合损耗, 同时改善对准容差, 设计了两种应用于光调制器中的模斑变换器(Spot-size Converter), 通过仿真对其传输损耗和模场耦合效率进行了比较, 其中采用混合结构的模斑变换器具有更优的性能。
模斑变换器 耦合损耗 对准容差 数值仿真 spot-size converter coupling loss alignment tolerance numerical simulation
楔形模斑变换器在利用硅基光子集成技术实现芯片间光互连中有着广泛的应用。文章概述了国内外楔形模斑变换器的最新研究进展。介绍了几种新型模斑变换器的结构及制作的工艺流程, 并对其性能及影响楔形模斑变换器耦合效率的几个因素进行了分析比较, 进而讨论了这几种模斑变换器存在的问题及进一步提高耦合效率的可能性。
硅基光子学 模斑变换器 耦合效率 silicon photonics spot-size converter coupling efficiency
中国科学院 半导体研究所 光电子研发中心,北京 100083
为了提高基于绝缘体上硅(Silicon on insulator,SOI)的Si微纳波导器件和光纤的耦合效率,设计了一种基于SOI和溶胶-凝胶杂化SiO2材料的新型微纳倒锥波导模斑转换器。此模斑转换器由Si微纳倒锥波导和溶胶-凝胶杂化SiO2矩形波导组成。使用三维束传播法(3D-BPM)对器件结构进行模拟优化。在倒锥波导模斑转换器的连接下,波长1550 nm,近似TE模的光源下的模拟结果显示:单模光纤和SOI的Si微纳波导的耦合效率达到了95%(损耗低于0.22 dB),结果可以有效地满足微纳波导器件和光纤的低损耗耦合的需要。
光学器件 模斑转换器 溶胶-凝胶 微纳波导 三维束传播法