Mach-Zehnder Interferometer Biochemical Sensor Based on Silicon-on-Insulator Rib Waveguide with Large Cross Section

Area of Science:

• Photonics and Optical Sensing
• Integrated Optics
• Biochemical Sensing

Background:

• Mach-Zehnder interferometers (MZIs) are crucial for biochemical sensing.
• Silicon-on-insulator (SOI) rib waveguides offer potential for high-performance photonic devices.
• Optimizing waveguide parameters is key to enhancing MZI sensor sensitivity and resolution.

Purpose of the Study:

• To propose a high-sensitivity MZI biochemical sensing platform using SOI rib waveguides.
• To optimize waveguide dimensions and MZI configuration for improved sensing performance.
• To demonstrate the potential for integration with existing optical and electronic systems.

Main Methods:

• Finite difference method (FDM) simulations for optimizing SOI rib waveguide evanescent field intensity, mode polarization, and cross-section dimensions.
• Two-dimensional finite-difference-time domain (2D-FDTD) simulations for analyzing medium-filled trenches in the MZI read-out configuration.
• Design and simulation of an MZI sensor with a 10 mm sensitive window using specific SOI rib waveguide dimensions at 1550 nm.

Main Results:

• Optimized SOI rib waveguide parameters (10 μm total height, 5 μm outside height, 2.5 μm width) achieved high sensitivity.
• A homogeneous sensitivity of 7296.6%/RIU was obtained for the EH-polarized mode.
• A detection limit of 2.74 × 10⁻⁶ RIU was achieved with 0.2% detector resolution.

Conclusions:

• The proposed SOI MZI platform demonstrates excellent sensitivity and a low detection limit for biochemical sensing.
• The large cross-section SOI rib waveguide offers efficient coupling with standard optical fibers, facilitating integration.
• This sensing platform has potential for remote sensing, in situ real-time detection, and Internet of Things applications.