Experimental Validation of the Sensitivity of Waveguide Grating Based Refractometric (Bio)sensors

Area of Science:

• Photonics and Sensing Technologies
• Optical Biosensors
• Waveguide Optics

Background:

• Theoretical models for waveguide grating (bio)sensor sensitivity have existed for decades.
• Experimental validation of these models across diverse parameters is lacking.
• Refractive index sensing is crucial for various scientific and industrial applications.

Purpose of the Study:

• To experimentally determine the bulk refractive index sensitivity of waveguide grating sensors.
• To compare experimental results with theoretical predictions.
• To investigate sensitivity across multiple film thicknesses, wavelengths, and light polarizations.

Main Methods:

• Experimental determination of effective refractive indices and sensitivity using coupling angles.
• Measurements conducted at various cover refractive indices.
• Utilized transverse electric (TE) and transverse magnetic (TM) polarized light across visible and near-infrared wavelengths.
• Theoretical sensitivity calculated by solving the waveguide mode equation for a three-layer system.

Main Results:

• Experimental confirmation of waveguide sensitivity for multiple film thicknesses, wavelengths, and polarizations.
• Demonstrated good agreement between experimental data and theoretical predictions.
• Quantified the relationship between bulk refractive index sensitivity and waveguide thickness.

Conclusions:

• Experimental validation of waveguide grating sensor theory across a range of parameters.
• The study provides crucial experimental data for the design and optimization of refractometric sensors.
• Confirms the reliability of theoretical models for predicting sensor performance.