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Emerging applications in wide-range optical fields require a common building block cell for dense photonic integrated circuits with high performance and multi-functionality. We present a flexible grating-assisted silicon microring resonator structure promising of generating several physical effects including slow light effect, Vernier effect and orbital angular momentum emitting for different scenarios. By presenting the design, optimization principle, and assessing the performances, we demonstrate that the device could achieve different purposes with the same design routine and fabrication process with slight changes of the geometry parameters, which is very attractive for the realization of versatile building block element.

Aiming for high-sensitivity refractive index biosensing, we investigate Fano resonance in a one-dimensional photonic crystal cavity-coupled microring resonator (PCMRR) on a silicon chip. Calculated results show that utilizing the asymmetric line shape of the Fano resonance, the detection limit can be reduced by a factor of 5 and the intensity detection sensitivity of PCMRR can be increased by a factor of 5 compared with a regular silicon-on-insulator, reaching the values of ~7.2 × 10-4 RIU and ~1.76 × 104 dB/RIU, respectively. Owing to its simplicity, compact footprint, and excellent performances, our device would be a promising candidate for optical label-free sensing applications.

Real-time and high-sensitivity biosensors are urgently needed in biochemistry. As one of the candidates, silicon-on-insulator (SOI) sensors exhibits excellent performances. However, there are still some limitations to hinder them to be applied to much wider scenarios. Fabrication tolerance is also required for the generalization of these micro- or nano-structure. In this work, we demonstrate an SOI waveguide biosensor for biochemical sensing with high sensitivity of 1.88 × 105 dB/RIU. Because of the compact structure and low demand for accuracy of fabrication, this device possesses better applicability and reliability.

Aimed at a high-performance biosensor for sensing biological molecules quickly and accurately, a novel nonuniform photonic crystal waveguide (NUPhCW) with a feedback loop is systematically investigated based on the mode-splitting effect. Thanks to the careful design of the nonuniform holes of NUPhCW with a feedback loop, the Autler-Townes splitting occurs in our device, and the spacing of two splitting resonance modes changes with the environmental refractive index, which is beneficial for achieving biosensing scenarios. Further, this integrated structure allows for self-referencing detection for immunity against environmental noise. Sensitivity of the NUPhCW is achieved at ∼117 nm/RIU, which is 2.6 times more than that of the common microring resonator, indicating that our proposed device structure would be promising for high-quality optical label-free sensing.