Surface-Enhanced Infrared Absorption Spectroscopic Chalcogenide Waveguide Sensor Using a Silver Island Film

Area of Science:

• Optical Sensors
• Spectroscopy
• Nanomaterials

Background:

• Chalcogenide waveguide sensors offer potential for chemical detection.
• Enhancing sensitivity in both liquid and gas phase sensing remains a challenge.

Purpose of the Study:

• To develop a surface-enhanced infrared absorption spectroscopic chalcogenide waveguide sensor.
• To improve sensing performance using a silver island film.
• To investigate its application in both liquid and gas phase detection.

Main Methods:

• Fabrication of chalcogenide waveguide sensors using lift-off and oblique angle deposition.
• Integration of silver island films of varying thicknesses.
• Characterization of surface morphology.
• Measurement of ethanol (liquid) and methane (gas) absorption spectra.

Main Results:

• The sensor with a 1.8 nm-thick silver island film showed the best performance.
• Achieved absorbance enhancement factors >1.5 for ethanol and >2.3 for methane.
• Demonstrated a methane limit of detection of ~4.11% with a 0.2 s averaging time.
• Derived a relationship between absorbance enhancement and waveguide loss.

Conclusions:

• The silver island film significantly enhances infrared absorption spectroscopy for waveguide sensors.
• The proposed sensor design is suitable for lab-on-a-chip applications.
• This approach offers improved sensitivity for liquid and gas phase chemical sensing.