基于硅基微机械谐振器的低功耗集成光环行器研究

Integrated optical circulators are key components in optical communication chips. In these devices, optical signals could be transmitted in a strict circular order while be blocked in the opposite order. Therefore, the integrated circulators could effectively ensure the transmission order and stability of optical signals, which have broad application prospects and great demands in the next generation optical communication networks. In order to solve the crucial challenges and physical problems in terms of high power consumption and narrow bandwidth, we make deep investigations on the opto-mechanical effect in silicon mechanical and free-hanging microring resonators (MRRs) and optimize the optical circulator model based on the free-hanging MRRs. Therefore, the power consumption of the optical circulator could be largely reduced. On the other hand, the tuning range of electrode is designed to be larger than the free spectral range of the MRR to effectively utilize multiple resonances and break the bandwidth limit. In this case, the working bandwidth of the circulator could be greatly expanded. Especially, we focus on the optimization of the optical force in the free-hanging microring resonator and enhancement of electrode modulation efficiency. The general target is to realize integrated optical circulators of low power consumption (<1mW), wide bandwidth (>30nm) and high isolation (>40dB). The research results of this project could provide an innovative solution and effective scheme for on-chip signal circular transmission with low power consumption and wide bandwidth, which have important scientific significance for silicon photonic chips to be applied in 5G technology and so on.

集成光环行器是光通信芯片中的关键元件，它能够严格控制信号按照特定的环路依次传输而禁止反向传输，从而有力地保障了传输信号的有序性和稳定性，在下一代光通信网络中有着广阔的应用前景和市场需求。针对集成光环行器功耗高和带宽窄等难点和关键物理问题，本项目通过深入研究硅基机械悬空微环中的光力效应机理，接着以悬空微环为基本单元优化光环行器模型，从而大幅度地降低光环行器的功耗；同时，设计电极的调谐范围大于微环的自由频谱范围，高效地利用了微环的多个谐振波长，从而突破了谐振器应用于光环行器领域的窄带宽限制，极大地扩展了环行器的工作带宽。本项目重点解决悬空微环中光力优化和热电极调制效率增强的问题，最终实现低功耗（<1mW）、大工作带宽（>30nm）和高隔离度（>40dB）的集成光环行器，为光信号在集成芯片上进行低功耗和宽带环路传输提供新思路和有效方法，对促进硅光子芯片实际应用于5G等技术具有重要的科学意义。

集成光环形器能够严格控制信号按照特定的环路依次传输而禁止反向传输，是构建片上全光网络的核心元件，有力地保障了光通信芯片上传输信号的有序性和稳定性，有着广阔的应用前景和市场需求。国际上报道的大多数集成光环行器方案功耗比较高而且工作带宽较窄，并且器件结构的端口数目难以扩展。本项目针对集成光环行器中的难点和关键物理问题，从理论分析、器件设计和工艺制作、测试验证三方面出发，提出并制作了硅基集成片上光环形器。建立了悬空微环实现非对称光传输的理论模型，解决了光环形器功耗高的问题；以实现最强的光力效应为目标，优化了悬空微环的各项结构参数，提升了光环形器的隔离度等性能；设计了以悬空微环为基本单元的光环行器整体模型，实现了宽带传输且端口数可扩展的光环形器。通过微纳器件加工，实际制作了多端口的集成光环形器，在低功耗条件下实现了高隔离度。在理论和方法上实现一定程度创新，良好地完成了研究目标。设计的集成光环形器功耗低、隔离度高、结构可扩展、制作成本低，为集成芯片上光信号的低功耗和宽带环路传输提供了有效解决方案，在光通信芯片和微波光子芯片中有着重要的科学意义和应用。在该项目的资助下，共发表影响因子大于2的SCI论文17篇（其中15篇为第一作者或者通讯作者），申请国家发明专利6项（已授权1项），培养硕士研究生6名，其中已毕业3名。项目结题成果整体上超过预期研究目标。