Design and Fabrication of Polarization-Independent Lithium Niobate Electro-Optic Modulator

• Main Authors: Chia-Wei Hsu, 許嘉維
• Other Authors: Way-Seen Wang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/16643859274295568418

碩士 === 國立臺灣大學 === 電子工程學研究所 === 100 === Novel polarization-independent lithium niobate electro-optic modulators operating at 1.55um are successfully designed and fabricated for demonstration. The proposed device, based on the structure of Mach-Zehnder interferometer, is an integration of a polarization splitter and two single-polarization electro-optic modulators. On the same Z-cut lithium niobate, the TE mode waveguide is fabricated by Zn and Ni co-diffusion, whereas the TM mode waveguide is fabricated only by Ga diffusion. Though three types of metal (Zn, Ni, and Ga) are deposited, only one diffusion step is needed, which greatly simplifies the device fabrication process. For the polarization splitter, the measured extinction ratios are 27.5dB and 24.3dB for the TE and TM modes, respectively. For the single-polarization electro-optic modulator, the device length is 3cm, and the polarization dependent loss is less than 0.69dB when the applied voltage is within the range of 0-100V, and it becomes as low as 0.05dB at two specific applied voltages 26V and 95V. These results show the proposed polarization-independent electro-optic modulator has good potential for practical application.