Design of Directional Coupler Structure in Electro-Optic Integrated Circuit Using Refractive Index Sensor Based on Silicon Nitride Substrate

Subject Areas : Journal of Optoelectronical Nanostructures

Sina Tahanazadeh ¹ , Sharifeh Shahi ^{2 *} , Atefeh Salimi Shahraki ³

1 - Department of Electrical engineering, Isf.C., Islamic Azad University, Isfahan, Iran
2 - Department of Biomedical Engineering and Laser and Biophotonics in Biotechnologies Research Center, Isf.C., Islamic Azad University, Isfahan, Iran
3 - Department of Electrical engineering, Isf.C., Islamic Azad University, Isfahan, Iran

Received: 2025-02-01 Accepted : 2025-08-20 Published : 2025-11-30

Keywords: Directional Coupler Waveguide, Fundamental Mode , Photonic Integrated Circuit (PIC), Refractive Index, Sensor,

Abstract :

Ansys Lumerical software, with its powerful MODE and FDTD modules, emerges as an indispensable tool for analyzing light behavior within electro-optical integrated circuits that play a vital role in fulfilling this critical needwithin intricate structures and evaluating their feasibility for many applications. The MODE module, equipped with the FDE and varFDTD solvers, excels in efficiently simulating light propagation, providing rapid results that are invaluable for initial comparisons and design exploration in based on increasing the efficiency. In this study, a simulated sensor was strategically integrated into a directional coupler structure. By meticulously analyzing light propagation through strategically placed monitors within this integrated system, were able to gain valuable insights into the sensor's performance. The findings demonstrated that the varFDTD solver within the MODE module proved highly effective in optimizing the design of the directional coupler based the TM mode behavior into the TE mode. As the light polarization changes, variations occurred at a width range between 0.66 to 0.83 micrometers.

This optimization resulted in a significant enhancement of the sensor's efficiency, ensuring its robust and reliable operation across a wide range of environmental conditions and operational scenarios.