Design and Fabrication of Lithium Niobate Surface Plasmon Resonance Sensors

• Main Authors: Chung-Hsun Li, 李忠勳
• Other Authors: Way-Seen Wang
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/87596665232887881617

碩士 === 國立臺灣大學 === 光電工程學研究所 === 94 === Lithium niobate (LiNbO3) based surface plasmon resonance (SPR) sensor is demonstrated in this paper. LiNbO3 possesses the birefringence and the good electro-optical (EO) effect. We use the birefringence to fabricate the waveguide where only TM-polarized wave can be guided on +Z-cut LiNbO3 with the proton-exchanged method. Then the thin film of gold and titanium dioxide (TiO2) are sequentially deposited on the surface of the waveguide. Gold is used to excite surface plasma wave (SPW) and the oxide layer can adjust the operated range of refractive index of analyte to 1.33 ~ 1.4. With 60nm-thick gold, 35 and 40nm-thick TiO2, SPR is successfully excited on LiNbO3 and the sensitivities are respectively determined to be 436.84nm/RIU and 501.32nm/RIU with wavelength interrogation, which agree well with the theoretical simulation. This waveguide-based SPR sensor requires no extra polarization controller. Thus the size of the SPR sensor system can be reduced further. In addition, LiNbO3 has good EO effect, which can be utilized to change the phase shift caused by SPR, and the highly sensitive sensor can be achieved by phase interrogation in previous papers. Therefore, the highly sensitive sensor system with the EO effect possessed by LiNbO3 has a great potential on fabrication cost and the size of the sensor system. We discuss the phase shift with the modeling and finish the design of the Mach-Zehnder based SPR sensor. The calculated sensitivity is as high as 9.62848 10-8 RIU.