Research On Novel Silicon Nanowire Waveguide And Resonator

Due to the compatibility with CMOS process, and the excellent performance in the optical telecommunication wavelength regime, silicon photonics has been researched extensively in recent years. In the paper, integrated silicon photonic devices with various functionalities are introduced, as well as their applications in optical interconnect an optical sensing. Then, the research about novel low-loss silicon waveguides and suspended ultrasmall disk resonator based on Silicon-On-Insulator (SOI) are put forward.Firstly, the source of the optical loss in planar photonic waveguide is studied, as well as the characteristics of the waveguide which may affect its loss performance. Considering the fabrication technique of the silicon nanowire waveguide, various methods that can reduce the loss of waveguide are put forward. On the basis of previous analysis and comparison, the fabrication of silicon waveguide via selective oxidation is presented. After that, the silicon nanowire waveguide with single mode propagation is realized with the ridge height of130nm, the one-side slab height of25nm and the width of1μm. A high quality factor ring resonator with the radius of100μm is also fabricated, with the quality factor of about2×lO4.Then, the paper presents the keynote research about suspended ultra-small disk resonator for optical sensing. The theory of the disk’s Whispering-Gallery-Mode (WGM) is briefly introduced, and the adoption of the suspended structure could elevate the quality factor and sensitivity of the disk sensor is expected. The bending loss and sensitivity are calculated with the radius of0.5μm-lμm for the disk resonator. According to the simulation results, the disk with a radius of0.8μm is employed, which has a moderate high quality factor and a60%improvement of the sensitivity compared to unsuspended structures. The coupling waveguide with one-side slab to support the suspended structure is designed for the coupling of the input optical signal. The suspended disk resonator with R=0.8μm and silicon height of340nm are fabricated, the width of the coupling waveguide is about305nm and the coupling gap is about65nm. After that, the sensing character of disk resonator is performed with different liquid solutions, which are different concentrations of NaCl solutions and various organic liquids. The measured sensitivity is about130nm/RIU and the quality factor is about100, the results are in good agreement with the simulation values.