CMOS兼容的小型化硅基光隔离器

Silicon photonic devices are compatible with CMOS processing, therefore they are amenable to low cost fabrication and large-scale integration. Furthermore, they can be monolithically integrated with silicon microelectronics. As such, silicon photonics promises to have revolutionary impact on optical interconnects, optical communications, optical signal processing and optical sensing. CMOS-compatible optical isolators are a key device research topic in silicon photonics. An optical isolator allows light to pass in one direction only. It is an indispensible component in many optical systems. Traditional optical isolators usually employ materials that are not compatible with the CMOS processing technology. Recently, CMOS compatible active silicon optical isolators based on electro-optic modulation have been proposed. However, preliminary experiments showed that its electrical power consumption was very high and optical isolation was low. This research project aims at introducing silicon photonic crystal waveguides into such an optical isolator. As slow light in such waveguides can enhance light-matter interaction, the interaction length and power consumption of such an active optical isolator can be significantly reduced. As such, higher optical isolation can be achieved at a normal electrical power consumption. The compact size and low power characteristics of the proposed isolator device will lift crucial barriers for isolators to be used in future large-scale silicon photonics integration. Furthermore, the physical mechanism research in this project can offer new perspectives on the basic science of slow light and the breaking of time-reversal symmetry.

硅基光子器件与CMOS工艺相兼容，可以以极低的成本制备并可大规模集成，近一步还可以与硅基微电子实现集成，因而可能在光互联，光通讯，光信号处理，和光传感等方面引起革命性的技术突破。CMOS兼容的光隔离器技术是硅基光子学领域的一个关键的器件研究方向。光隔离器具有单向通光的特性，在许多光学系统中是不可或缺的器件。现有较成熟的光隔离器技术采用的材料与CMOS加工技术不兼容。近来，CMOS兼容的硅基主动式(active)光隔离器构想被提出并受到了关注。但初步实验结果表明其功耗较高，光隔离度较低。本项目希望在硅基主动式光隔离器引入光子晶体波导，利用慢光效应对光与物质作用的增强效应，缩短器件长度，降低功耗，以达到更高的光隔离度。这里的CMOS兼容光隔离器所具有小型化，低功耗的优点将为该器件在未来大规模光子集成中的应用扫清障碍。本项目的机理研究还可为慢光效应，时间反演对称性破缺等基础研究课题提供新的视角。

硅基光子器件与CMOS工艺相兼容，可以以极低的成本制备并可大规模集成，在光互连，光通讯，光信号处理和光传感等方面有广泛的应用潜力。CMOS兼容的光隔离器是硅基光子学领域的一个关键的器件研究方向。光隔离器基于光学非互易现象，常见CMOS兼容材料不具有光学非互易特性，因而现有较成熟的光隔离器技术采用的材料与CMOS加工技术不兼容。近来，CMOS兼容的硅基光隔离器构想被提出并受到了关注。本项目对基于光子晶体波导、微谐振腔的微纳结构的小型化光隔离器原理进行研究。设计了适用于主动式光隔离器的具有特定频差特性光子晶体波导结构。在光子晶体慢光波导热光移相器实验中验证了慢光增强效应，器件功耗降低约6倍；在100微米长的光子晶体波导调制器实验中，在8.5Gb/s～14Gb/s的调制速率下得到了较为清晰的眼图。对硅基微腔与耦合微腔结构的非线性特性进行了理论建模，通过硅基非对称Fabry-Perot腔和微环耦合，以及非线性效应，实现了简单、结构紧凑、功率可调的可反转硅基光学二极管。器件在2.05dBm的输入功率和-6.95dBm的输入功率下，分别实现了-15.38dB和30.88dB的非互易传输系数。此外，在高Q值微腔，可调Q微腔，石墨烯辅助微腔开关等方面取得进展，在并联双跑道谐振腔中实现了无外加数－模转换器(DAC-less)100Gb/s四电平(PAM-4)调制，在器件封装、混合集成、电光器件工艺偏差研究等方面取得了成果，这些结果为进一步全面提升微腔非互易器件的性能提供新思路和技术储备。