Investigation of LPG-SPR sensors using the finite element method and eigenmode expansion method

Area of Science:

• Photonics and Sensor Technology
• Computational Electromagnetics
• Nanophotonics

Background:

• Traditional couple-mode theory for long-period fiber-grating surface-plasmon-resonance (LPG-SPR) sensors has limitations in simulation accuracy and design flexibility.
• Existing numerical methods often struggle with 3D analysis and accurate prediction of spectral characteristics.

Purpose of the Study:

• To propose a novel, visual, and simplified numerical simulation method for LPG-SPR sensors.
• To overcome the limitations of traditional methods by enabling 3D design and analysis.
• To reduce the learning curve for LPG-SPR sensor research and application.

Main Methods:

• Combines the finite element method (FEM) to solve for guided modes and surface plasmon waves.
• Utilizes the eigenmode expansion method (EEM) to calculate power transfer phenomena.
• Employs a rigorous, simple, and complete design process with graphical simulation capabilities.

Main Results:

• The proposed method demonstrates superior performance compared to finite-difference time-domain and beam propagation methods.
• Achieves 3D design and analysis capabilities, unlike previous methods focusing on large periodic components.
• Exhibits rapid scanning of LPG periods and accurate alignment of design and maximum transmission wavelengths.
• Verified LPG-SPR sensor performance with a resolution of ~-45 dB and sensitivity of ~27000 nm/RIU.

Conclusions:

• The developed graphical simulation technique simplifies LPG-SPR sensor design and analysis.
• This method significantly reduces the time and expertise required for developing advanced LPG-SPR sensors.
• The approach offers a powerful tool for researchers and engineers in the field of optical sensing.