抗諧振反射光波導化學感測元件

Abstract

本論文探討應用抗諧振反射光波導結構設計化學感測元件,應用抗諧振反射光波導結構有以下的優點: 1) 抗諧振反射光波導的核之折射率及大小可設計與單模光纖相符以提高耦合效率; 2) 抗諧振反射光波導可以製作在高折射率基板上,與半導體製程相容。為了改進感測度,我們探討了: 1)高折射率覆蓋層抗諧振反射光波導感測元件; 2) 兩段式高折射率覆蓋層抗諧振反射光波導感測元件; 3)雙抗諧振反射光波導感測元件；4)改進型雙抗諧振反射光波導感測元件,找出具高感測度之各感測元件結構最佳元件參數,並以Finite Difference Beam Propagation Method (FDBPM) 驗證光束傳輸特性。

ARROW evanescent-wave chemical sensors are investigated. There are some advantages to use an ARROW instead of a conventional waveguide for an evanescent-wave sensor: 1) the core index and size of ARROW can be compatible with single-mode fiber index and diameter, which provides efficient connections to fibers; 2) ARROW can be fabricated on high refractive index substrates, and the fabrication is compatible with IC processes. To enhance the sensitivity of ARROW sensors we proposed: 1) single ARROW sensor with a high index overlay; 2) two-step ARROW sensor with a high index overlay; 3) dual ARROW sensor; 4) modified dual ARROW sensor. The optimum device parameters are investigated for higher sensitivities. Finite Difference Beam Propagation Method (FDBPM) was used to confirm the device beam-propagation characteristics. 2 Modeling Theories for Optical Waveguide Evanescent-Wave sensors And ARROW Devices 2.1 Multilayer Characteristic matrix method 2.2 Modal electric field normalization 2.3 Cutoff thickness of a conventional waveguide 2.4 Loss of an ARROW due to a high index substrate 2.5 Absorption coefficient of the chemical species in the cover region 2.6 Sensitivity 2.7 Finite difference beam propagation method 2.8 Mode excitation at the step discontinuity 2.9 Effective index equation method 3 Sensors based on ARROW structures 3.1 Single ARROW sensor 3.2 Single ARROW sensor with a high index overlay 3.2.1 Single ARROW sensor with a high index overlay 3.2.2 Two-step ARROW sensor with a high index overlay 3.3 Dual ARROW sensors 3.3.1 Beam propagating in the coupling region 3.3.2 Beam propagating in the sensing region 3.4 Modified dual ARROW sensors 3.4.1 Beam propagating in the coupling region 3.4.2 Beam propagating in the sensing region 3.5 Summary 4 Conclusions