Bent silicon slot waveguides with both low loss and low nonlinearity

• Published in: Optical and quantum electronics 2020-10, Vol.52 (10), Article 445
• Main Authors: Xu, Yameng, Li, Jiaxuan, Kong, Mei, Chen, Chen
• Format: Article
• Language: English
• Subjects: Bend radius; Characterization and Evaluation of Materials; Cladding; Computer Communication Networks; Confinement; Electrical Engineering; Lasers; Nonlinearity; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Silicon; Silicon dioxide; Waveguides
• ISSN: 0306-8919; 1572-817X
• DOI: 10.1007/s11082-020-02569-1

With the development of highly integrated linear optical systems, both low loss and low nonlinearity are demanded for silicon slot waveguides with a small bending radius. In this paper, we calculate the variations of loss and nonlinearity with the bending radius of air-cladding and silica-cladding slot waveguides, and the mechanisms underlying the variations are revealed. We show that slot waveguides with symmetric silicon arms cannot possess low nonlinearity and low loss simultaneously due to the serious optical power leakage to the substrate. To solve this issue, asymmetric silicon arms are employed. By increasing the width of the inner arm, the high power confinement in the slot can be ensured, and this also makes the simultaneous low loss and low nonlinearity possible. We show that the silica-cladding slot waveguide under a 5 μm radius can obtain power confinement, loss and nonlinearity as respectively 40%, 1.17 × 10 −4  dB/μm and 16.41/W/m, which are all comparable with those in the straight slot waveguide.