Class modal analysis of a thin multi-trench-assisted liquid-filled optical waveguide coupler for simultaneous...

Area of Science:

• Photonics and Sensing
• Optical Engineering
• Chemical Detection

Background:

• Optical waveguide couplers are crucial for sensing applications.
• Existing methods for chemical detection via optical means require novel approaches for enhanced sensitivity and specificity.

Purpose of the Study:

• To present a novel thin multi-trench-assisted optical coupler for multi-sensing chemical detection.
• To demonstrate the tunability of the coupler's properties by altering the refractive index of trench-filling liquids.

Main Methods:

• Analysis of transverse electric (TE) and transverse magnetic (TM) modes using the scalar finite difference method (FDM).
• Propagation of eigenmode profiles (approximated as Gaussian pulses) along the multi-trench structure.
• Utilizing variable discretization steps in FDM for enhanced accuracy.

Main Results:

• The coupling period of the optical coupler can be effectively tuned by modifying the refractive index of the trench regions.
• Demonstrated the capability of the coupler to differentiate between various chemicals based on refractive index changes.
• Validated the design through several examples showcasing different trench configurations and chemical compositions.

Conclusions:

• A new scheme for a thin multi-trench-assisted optical coupler has been proposed for chemical sensing.
• This approach offers a promising method for detecting adulteration in products like beverages and in medical diagnostics.
• The tunability of the coupling period provides a versatile platform for developing advanced chemical sensors.