Ring resonator is an essential element in silicon integrated circuit, it is widely used as filter, wavelength multiplexer and switch in single-mode operation regime. As the rapid development of mode division multiplexing (MDM) technique, ring resonator that can process multi-mode signals simultaneously and uniformly is highly desired. However, the severe modal dispersion makes identical transmission for different modes very hard. In this paper, by breaking through the limitation of conventional multi-mode manipulation design with evanescent coupling or mode interference, we propose and demonstrate a multi-mode ring resonator (MMRR) inspired by the free space geometric optics. Arbitrary number of supporting modes can be achieved by simply widening the waveguide width. For proof-of-concept demonstration, an MMRR supporting four modes is fabricated with uniform transmittance. Furthermore, architecture of cascaded four MMRRs are also demonstrated experimentally.

中文翻译：

---

硅集成多模环形谐振器

环形谐振器是硅集成电路中必不可少的元件，在单模工作方式下，它被广泛用作滤波器，波长复用器和开关。随着模分复用（MDM）技术的迅速发展，人们迫切希望能够同时且均匀地处理多模信号的环形谐振器。但是，严重的模态色散使得针对不同模式的相同传输非常困难。在本文中，通过突破传统的多模式操纵设计的局限性，即e逝波耦合或模式干扰，我们提出并演示了一种受自由空间几何光学启发的多模式环形谐振器（MMRR）。可以通过简单地加宽波导宽度来实现任意数量的支撑模式。为了进行概念验证演示，以均匀的透射率制造了支持四种模式的MMRR。此外，还通过实验演示了级联的四个MMRR的体系结构。