Resonant Gas Sensing in the Terahertz Spectral Range Using Two-Wire Phase-Shifted Waveguide Bragg Gratings

Area of Science:

• Optoelectronics
• Terahertz Technology
• Chemical Sensing

Background:

• Optical gas sensors require low-cost, compact, flexible, and robust designs for practical use.
• Terahertz (THz) frequency band offers unique properties for sensing applications.

Purpose of the Study:

• To develop a waveguide-based resonant gas sensor operating in the terahertz frequency band.
• To achieve high sensitivity and resolution for gas detection using a novel sensor design.

Main Methods:

• Utilized micro-encapsulated two-wire plasmonic waveguides and a phase-shifted waveguide Bragg grating (WBG).
• Designed a modular semi-sealed structure for efficient analyte-radiation interaction.
• Optimized spectral response by tailoring cavity length and grating periods.

Main Results:

• Developed a THz gas sensor operating around 140 GHz with a sensitivity of 144 GHz/RIU.
• Achieved a high resolution of 7 × 10^-5 RIU.
• Demonstrated real-time gas sensing of glycerol vapor via spectral response monitoring.

Conclusions:

• The phase-shifted grating-based THz resonant gas sensor shows significant potential for gas sensing.
• This technology opens new opportunities for monitoring gaseous analytes with high precision.