本論文以SOI結構為基礎，提出一個改良的極化分離器，利用肋狀波導去耦合現象來設計對稱型定向耦合器，在結構中新增一個材料與波導結構相同的平台，增加去耦合機制，將去耦合現象及TM模態截止效應分開，可避免高階模態產生，且有效的將元件尺寸縮小，使TM模態達到不耦合，而TE模態因對稱波導的折射率相等，在設計得當的耦合距離滿足相位匹配條件，將耦合至另外一根波導中，達到極化分離的效果。首先固定波導芯的寬度與高度，設計了不同的平台高度與對應板狀結構高度，板狀結構高度80nm、平台高度超過160nm會出現高階模態。透過分析交叉極化耦合效應發現，隨著平台高度與板狀結構高度下降，都可有效的抑制交叉極化耦合效應，最終板狀結構高度80 nm，平台高度125 nm，為結構參數。

In this paper, we propose a constant voltage voltammetry potentiostat for detecting caffeine utilizes a microprocessor chip based on the ARM Cortex-M3 design, specifically the Silicon Labs EFM32, as its control core. The instrument employs commercially available printed circuit electrode boards as caffeine sensors, with control facilitated through the EFM32’s Universal Asynchronous Receiver-Transmitter (UART), interfacing with a LabVIEW human-machine interface on a personal computer. For system verification, standard solutions of different caffeine concentrations are applied to the detection area of the printed circuit electrodes. Two common electrochemical measurement techniques are utilized: cyclic voltammetry and fixed voltage voltammetry. Through cyclic voltammetry analysis of the caffeine standard solutions, the oxidation peak potential of the sensor is obtained. This oxidation peak potential is then used to set the voltage for fixed voltage voltammetry, forming the basis for the electrochemical analysis method of detecting caffeine using the sensor. Experimental results are observed through the LabVIEW interface. Finally, a calibration curve for the developed caffeine sensor is established, and the results are compared with data obtained from a commercial potentiostat. In the future, the caffeine sensor designed in this system could be integrated into beverage cups for applications in detecting the caffeine concentration in commercially available beverages. This would enable users to quickly determine the caffeine content of their drinks, helping them avoid excessive caffeine intake throughout the day.