Sensitivity enhancement of bimodal waveguide interferometric sensor based on regional mode engineering

Area of Science:

• Photonics
• Optical Sensing
• Integrated Optics

Background:

• Bimodal waveguides are crucial for interferometric sensing applications.
• Improving sensor sensitivity and detection limits is a key challenge in optical sensing.
• Existing designs often face limitations in analyte interaction and sensitivity.

Purpose of the Study:

• To propose and experimentally validate a novel bimodal waveguide based on regional mode engineering (BiMW-RME).
• To enhance the sensitivity of common-path interferometric sensors through optimized mode interaction.
• To demonstrate a significant improvement in phase sensitivity and detection limit.

Main Methods:

• Fabrication of a bimodal waveguide with patterned SiO2 cladding on a silicon-on-insulator (SOI) platform.
• Utilizing the orthogonality of guided modes for reduced reference mode-analyte interaction.
• Experimental characterization of the sensor's phase sensitivity and detection limit.

Main Results:

• The BiMW-RME sensor achieved a phase sensitivity of 2766 π rad/RIU/cm.
• A detection limit of 2.44×10^-5 RIU was experimentally demonstrated.
• Achieved a 2.7-fold increase in sensitivity compared to conventional bimodal waveguide sensors.

Conclusions:

• The proposed BiMW-RME design significantly enhances sensor sensitivity by controlling mode interaction.
• This novel approach offers a promising strategy for improving common-path interferometric sensor performance.
• The findings present a new avenue for developing highly sensitive optical sensing devices.