Electroabsorption modulators and laser diodes for free space optics and on-chip applications

用于自由空间光学和片上应用的电吸收调制器和激光二极管

• 批准号: 2036167
• 金额: --
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2036167
• 关键词: Electroabsorption; modulators; laser; diodes; free

The main objective is to design a modulator that can be fitted to an unmanned aerial vehicle (UAV) to provide an optical datalink that is fast, secure and robust. There has been a significant amount of research conducted into free space optical communication systems in the last decade alone and a modulating retro-reflector system is the best solution for a lightweight and efficient modulator. The bulk of this work has focussed on cat's eye retro-reflector (CER) systems, rather than the simpler corner-cube retro-reflector (CCR), due to limitations on size and speed that come with the larger CCR. CER systems are generally less robust than CCR due to high precision required in lens positioning, potential optical aberrations and quite severe limitations on field of view. The primary aim for this project is to utilize modern manufacturing and fabrication techniques to construct a large, pixelated electro absorption CCR modulator. Advances in manufacturing techniques have created more possibilities in type-II semiconductor systems and these will form the basis for further research, modelling and testing. Antimony based compounds show great potential for application at 1.55um wavelength. Manufacturing and fabrication developments allow for the construction of precise type-II multiple quantum well heterostructures that can be engineered to this specific use. The material system which appears to be the most applicable combines GaSb quantum wells with AlGaSb barriers. This multiple quantum well active region will then be fabricated within a P-I-N diode structure. Type-II materials have strong confinement of electrons and holes with spatial separation, thus generally holes are confined to the well material and electrons to the barrier material. This can lead to very large shifts in the optical absorption of the material when under an electrical bias. This is ideal for providing a high extinction ratio.Furthermore, by pixelating this material, high speed data transmission can be achieved without compromising the field of view of the retro-reflector. Another aim for the project is to create 'smart' pixels that will only be active upon incident light of wavelength 1.55um. This will greatly reduce the overall power consumption of the modulator. Other considerations to optimise the system will be the temperature stability of the material, contrast ratio and insertion loss. The intention is that the PhD will also characterise the performance of as-grown structures.

主要目标是设计一种可安装到无人机 (UAV) 上的调制器，以提供快速、安全和稳健的光学数据链路。仅在过去十年中，就对自由空间光通信系统进行了大量研究，调制后向反射器系统是轻质高效调制器的最佳解决方案。这项工作的大部分集中在猫眼回归反射器 (CER) 系统上，而不是更简单的角锥立方体回归反射器 (CCR)，因为较大的 CCR 会带来尺寸和速度的限制。由于镜头定位所需的高精度、潜在的光学像差以及视场的严格限制，CER 系统的稳健性通常不如 CCR。该项目的主要目标是利用现代制造和制造技术构建大型像素化电吸收 CCR 调制器。制造技术的进步为II型半导体系统创造了更多可能性，这些将构成进一步研究、建模和测试的基础。锑基化合物在 1.55um 波长下显示出巨大的应用潜力。制造和制造的发展允许构建精确的 II 型多量子阱异质结构，可以针对这种特定用途进行设计。最适用的材料系统是将 GaSb 量子阱与 AlGaSb 势垒相结合。然后，该多量子阱有源区将在 P-I-N 二极管结构内制造。 II型材料对电子和空穴具有强烈的空间隔离约束，因此通常空穴被限制在阱材料中，电子被限制在势垒材料中。当处于电偏压下时，这可能导致材料的光学吸收发生非常大的变化。这非常适合提供高消光比。此外，通过对这种材料进行像素化，可以在不影响后向反射器视场的情况下实现高速数据传输。该项目的另一个目标是创建“智能”像素，仅在波长为 1.55um 的入射光下才会激活。这将大大降低调制器的整体功耗。优化系统的其他考虑因素包括材料的温度稳定性、对比度和插入损耗。其目的是，博士还将描述现有结构的性能特征。