SGER: Index Switchable III-nitride Planar Lightwave Circuits for Optical Communications

在过去的十年里，III-氮化物材料在半导体研究中占据了中心舞台，主要集中在作为工作在可见光和紫外区的光子器件的应用上。PI系统地研究了工作在近红外波段的III型氮化物的性质，包括折射率、光学同素、双折射和温度敏感性。他开发了基于AlGaN/GaN平面光波电路的各种光子器件，如工作在1550 nm波长的波导耦合器和阵列波导光栅(AWG)。由于III-氮化物是半导体材料，载流子注入可以用来调制折射率和改变波导的相位延迟。例如，在AlGaN/GaN p-i-n异质结制作的AWG的每个干涉臂上增加一个电极，就可以使波分复用器实现高速切换。显然，载流子引起的折射率变化是实现高速全光分组交换真正功能器件的关键一步。他建议在平面光波电路中设计、开发和优化AlGaN/GaN基p-i-n异质结结构，以实现载流子注入和折射率调谐。理论工作将集中在p-i-n异质结结构设计和载流子引起的折射率变化的效率上，包括带隙填充、带隙收缩和自由载流子吸收。实验工作将集中于AlGaN/GaN基p-i-n异质结光波导的制备、表征和优化。这一方案的智能优点在于引入了一种新的材料群，用于光通信。利用载流子注入实现折射率的快速调谐是实现高速光开关的关键，这一方案的广泛影响是双重的。从应用的角度来看，这项研究的结果将使更广泛的应用成为可能，这将在光通信中产生巨大的影响。从材料科学的角度来看，人们将对III-氮化物半导体的物理和物理性质有更深入的了解。III-氮化物的独特性质使其在光通信的红外波长区具有很好的导光和光开关能力，从而可能创造出具有前所未有的性质和功能的光子器件。

0532610HuiOver the last decade, III-nitride materials have occupied the central stage in thesemiconductor research with a predominant focus on applications as photonic devicesoperating in the visible and UV regions. The PI systematically investigated the properties of IIInitrides operating in the near infrared wavelength region, including refractive indices, opticallosses, birefringence and temperature sensitivities. He has developed various photonicdevices based on AlGaN/GaN planar lightwave circuits, such as waveguide couplers andarray waveguide gratings (AWG) operating in 1550nm wavelength.Since III-nitrides are semiconductor materials, carrier injection can be used to modulate therefractive index and to change the phase delay of the waveguide. Adding an electrode oneach interference arm of an AWG made by AlGaN/GaN p-i-n heterojunction, for example,could make a wavelength demultiplexer switchable at high speed. Obviously, carrier-inducedindex change is a key step toward a real functional device for high-speed all-optical packetswitch. He proposes to design, develop and optimize AlGaN/GaN-based p-i-n heterojunctionstructure in planar lightwave circuits to realize carrier injection and index tuning. Thetheoretical work will be focused on the p-i-n heterojunction structural design and theefficiency of carrier-induced index change, including bandfilling, bandgap-shrinkage andfree-carrier absorption. The experimental work will concentrate on the fabrication,characterization and optimization of the AlGaN/GaN-based p-i-n heterojunction waveguidedevices.The intellectual merit of this proposal lies in the introduction of a new material group forapplications in optical communications. Fast tuning of refractive index by carrier injection isthe key to realize high-speed optical switch.The broader impact of this proposal is two-fold. From the application point of view, theresult of this research will enable a wide array of applications, which will have enormousimpact in optical communications. From the material science point of view, a much greaterand fundamental understanding will be gained for III-nitride semiconductors in terms of theiroptical and physical properties.The unique properties of III-nitrides make them attractive for guiding and switch of light inthe infrared wavelength region for optical communications, which may allow the creation ofphotonic devices with unprecedented properties and functionalities.