We propose a coupled-tolerant subwavelength photonic racetrack resonator (PRR) on the silicon-on-insulator (SOI) platform, in which a subwavelength grating (SWG) PRR is coupled to a symmetrical SWG bus waveguide. The material equivalent refractive index can be manipulated by the SWG characteristic and thus an additional fabrication degree of freedom can be achieved. The resonant characteristics can be improved significantly by controlling the pillar size and increasing the interaction length between SWG racetrack and bus waveguide (RBW). The simulation results show that the PRR has a high-quality factor and large extinction ratio around 1550nm. Two groups of SWG and strip waveguide (SW) PRRs are fabricated. The fabrication tolerance is tested when fabrication error is changed from 0 to 20 nm and the quality factor is more than 7000 in de-ionized water. The testing results show that the tolerance in SWG-PRR has a 2.0-fold improvement than that in the SW-PRR. Then a fabricated SWG-PRR is employed to monitor different concentration glycerol injected on the chip. An optimal quality factor of 9500 around 1550 nm and bulk sensitivity of 412± 0.5 nm/RIU are achieved. Therefore, the structure is a potential candidate for label-free sensing in medical diagnosis and environmental monitoring.

Rural distribution networks have complex structures and numerous branches, making it difficult to locate the fault point when a fault occurs. This article studies the precise positioning problem of single-phase grounding faults in complex rural distribution networks. A new method for locating multi-terminal traveling wave faults based on the principle of time information matching is proposed. Firstly, according to the distribution network structure, a time database of the traveling wave arrival time of each detection device is established in advance. Then, after the fault occurs, the time of detection device is compared with the database, and the section of the fault point is screened. Finally, the double-terminal traveling wave positioning method is used to determine the precise location of the fault. The simulation results show that this method could be applied to all kinds of complex fault situations. It is easy to achieve, with high accuracy and fewer errors, and it is not affected by the type of short circuit, transition resistance, initial phase angle of the fault, or fault location. It effectively solves the problem of fault location in rural distribution networks of a power grid.

To achieve a large filtering band range at 1550nm of communication C band, a compact one-dimensional Photonic crystal structure-based microwave photonic filter (1DPhC-MPF) is proposed. The 1DPhC-MPF structure consists of a strip waveguide and a group of periodical holes arranged in the strip waveguide. By three-dimensional finite-difference time-domain (3D-FDTD) simulation, a biggest Photonic bandgap (PBG) of 51.85 THz could be achieved when the width of waveguide, the period and the R of holes are equal to 0.6μm, 0.4μm and 0.15μm, respectively. When the light is injected in the left of the waveguide, a biggest filtering band range (FBR) of 362.6nm could be achieved in the transmission spectrum. The transmission efficiencies could be reduced gradually with the increasement of filtering hole. The efficiencies are reduced to zero when the number of filtering hole is larger than 5. Therefore, the calculation results indicate that the proposed 1DPhC-MPF is an excellent candidate of filter for the optical interconnection device around 1550nm.