Study of electrically tunable, rapid response and low-loss SiN ring resonator using blue phase liquid crystal
| Autor: | Yuan-Cheng Li, 李元正 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 Ring resonators usually made of SiN (refractive index=1.6~2) or silicon (refractive index=3.4) possess wavelength selectivities and have been widely used in integrated optical circuits. The resonant wavelengths of ring resonators can be tuned by varying the effective index of ring resonators. Due to the nematic liquid crystals can function as phase modulation materials, they can be employed as the cladding of ring resonators to provide high tunability. However, the scattering loss raises due to the lower order of the nematic liquid crystal alignment. In addition, the response time is long for the nematic liquid crystal, which reduces the applications of the ring resonators. In this study, we propose a tunable low-loss SiN ring resonator with a blue phase liquid crystal (BPLC) cladding. The BPLC is an optically isotropic material with short response time. By apply an electric field, the Kerr effect would be induced due to the local reorientation, lattice deformation and phase transition of the BPLC, leading to the effective index variation and the resonant wavelengths shift of ring resonators. Due to the refractive index of SiN is close to the BPLC, a very wide tuning range of 2.85 nm for TM mode can be achieved. In addition, the response time of the ring resonators with BPLC cladding can be kept at sub-millisecond level as the voltage is smaller than 140V. The proposed BPLC ring resonator also demonstrate a high Q-factor owing to the low scattering loss of the BPLC. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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