为了探究鼎形微环谐振器的耦合区数量对输出的影响，建立了鼎形微环谐振器的物理模型。利用传输矩阵法对鼎形微环谐振器的物理模型进行研究。分析了不同耦合区数量对鼎形微环谐振器输出的影响。实验结果表明，随着耦合区数量的增加，在1.54~1.56 μm工作波长范围内谐振峰的数量增加，半高全宽FWHM越小，品质因子Q则越大，器件的储能性能越好，并且还能实现对特定波长的滤波作用。耦合区数量对鼎形微环谐振器性能有着很大影响，在设计时根据实际需要选择耦合区数量。

为实现高灵敏度及高品质因数的折射率传感特性，设计了一种基于槽型相移布拉格光栅的微环谐振器结构。该结构由槽型直波导内嵌相移布拉格光栅耦合单实波导微环构成。结构中离散态光模式与连续态光模式相互干涉产生了Fano共振。利用传输矩阵法量化谐振器中各部分的光场分布，分析系统的传输原理。采用时域有限差分法对提出的器件结构进行仿真模拟，并对结构物理参数进行优化。模拟结果表明该结构的品质因数达到25 729，比传统微环谐振器提高了3倍以上，消光比为18.65 dB，高出传统微环谐振器6.46 dB，折射率灵敏度达到122 nm/RIU，且该谐振器结构简单。所提出的结构在传感应用中具有一定的优势。

Silicon nitride (Si₃N₄) waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics. Indeed, state-of-the-art ultralow-loss Si₃N₄ waveguides are all fabricated using complex fabrication processes, and all of those reported that high Q microring resonators (MRRs) are fabricated in laboratories. We propose and demonstrate an ultralow-loss Si₃N₄ racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide. The MRR is fabricated by the standard multi project wafer (MPW) foundry process. It consists of two multimode straight waveguides (MSWs) connected by two multimode waveguide bends (MWBs). In particular, the MWBs are based on modified Euler bends, and an MSW directional coupler is used to avoid higher-order mode excitation. In this way, although a multimode waveguide is used in the MRR, only the fundamental mode is excited and transmitted with ultralow loss. Meanwhile, thanks to the 180 deg Euler bend, a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195 μm and a waveguide width of 3 μm is achieved. Results show that based on the widely used MPW process, a propagation loss of only 3.3 dB / m and a mean intrinsic Q of around 10.8 million are achieved for the first time.

The large-photon-number quantum state is a fundamental but nonresolved request for practical quantum information applications. We propose an N-photon state generation scheme that is feasible and scalable, using lithium niobate on insulator circuits. Such a scheme is based on the integration of a common building block called photon-number doubling unit (PDU) for deterministic single-photon parametric downconversion and upconversion. The PDU relies on a 10⁷-optical-quality-factor resonator and mW-level on-chip power, which is within the current fabrication and experimental limits. N-photon state generation schemes, with cluster and Greenberger–Horne–Zeilinger state as examples, are shown for different quantum tasks.

在微环谐振器耦合区添加模式分离器，提出一种硅光混合集成的波长复用和模式复用的结构，以解决微环谐振器无法进行模式分离的问题。该微环谐振器的品质因子为3 692，3 dB光学带宽为52 GHz，自由光谱范围为1.03 THz，TE₀模式产生的串扰为-11.0 dB，插入损耗低至-0.66 dB。基于此，提出一个双模式输入的发射-接收的模式复用系统。仿真结果显示该系统可以有效分离TE₀和TE₁模式，且微环具有波长选择能力。系统复用器和解复用器在C波段可以实现超紧凑的波长/模式复用结构。此外，制造公差从-10 nm到+15 nm内滤出端口有大于1 dB的响应，传输端口有小于-20 dB的响应。该微环结构能够同时实现模式和波长选择功能。