Polarization Splitters Using Subwavelength Grating Structures

• Main Authors: Priska-Rouli Siregar, 欣芮佳
• Other Authors: Chia-Chien Huang
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5198007%22.&searchmode=basic

碩士 === 國立中興大學 === 物理學系所 === 107 === Polarization beam splitter (PBS) is an essential component in the photonic integrated circuits (PICs). It is used to separate transverse electric (TE) and transverse magnetic (TM) polarizations while using high-contrast of refractive index materials to build up optical devices based on a silicon-on-insulator (SOI) platform. We know that there are several kinds of waveguide structures such as, strip/channel, rib/ridge, hybrid plasmonic, photonic crystal, slot, and subwavelength grating (SWG) waveguides. Among them, the SWG structures open up unique possibilities of advancing the integration of complex functionalities in PICs, and many high-performance PICs have been proposed in the SOI platform. SWG waveguides consist of periodic segments of low and high refractive index materials, with a pitch less than the operating wavelength. In this work, we propose a PBS operated at a wavelength of 1550 nm using SWG structures as the coupling waveguide between two Si waveguides guiding TE and TM modes. The TM mode propagates along a bar channel while the TE mode couples to another the cross channel by matching the phases of the two Si channels. The upper cladding is air and the substrate is SiO2. The height and width of the two Si waveguides are set to be 340 nm and 240 nm, respectively. We design the middle SWG waveguide to optimize the performances of the proposed PBS by analyzing the dimension of the SWG structure. The polarization extinction ratios (PERs) achieve 24 dB and 7 dB for TM and TE, respectively, while the insertion losses (ILs) are 0.2 dB and 2.9 dB for TM and TE, respectively.