Microchannel-based plasmonic refractive index sensor for low refractive index detection.

Area of Science:

• Photonics
• Nanotechnology
• Chemical Sensing

Background:

• Surface Plasmon Resonance (SPR) sensors are crucial for detecting minute changes in refractive index.
• Photonic Crystal Fibers (PCF) offer unique light-confining properties for enhanced sensing.
• Existing PCF-SPR sensors face limitations in sensitivity and resolution for low refractive index detection.

Purpose of the Study:

• To develop a highly sensitive and high-resolution PCF-SPR sensor for low refractive index (RI) detection.
• To investigate the performance of gold (Au) as a plasmonic material and TiO2 as an adhesive layer in a microchannel PCF-SPR setup.
• To demonstrate the sensor's potential for practical applications requiring accurate RI measurements.

Main Methods:

• Fabrication of a microchannel incorporated PCF.
• Coating the PCF with a thin layer of gold (Au) as the plasmonic material, using TiO2 as an adhesive layer.
• Experimental setup for surface plasmon resonance detection using near-infrared wavelength.
• Utilizing both wavelength and amplitude interrogation methods for data analysis.

Main Results:

• Achieved maximum sensitivities of 51,000 nm/RIU (wavelength interrogation) and 1872 RIU⁻¹ (amplitude interrogation) in the RI range of 1.22 to 1.37.
• Obtained resolutions of 1.96×10⁻⁶ RIU and 9.09×10⁻⁶ RIU using wavelength and amplitude interrogation, respectively.
• Reported a maximum figure of merit (FOM) of 566, indicating excellent sensing performance.

Conclusions:

• The proposed microchannel PCF-SPR sensor demonstrates superior sensitivity and resolution compared to existing PCF-SPR sensors for low RI detection.
• The sensor design is practical and feasible, utilizing readily available materials like gold and TiO2.
• The sensor is a promising candidate for applications demanding high-accuracy RI detection, including pharmaceutical inspection, leakage monitoring, and bio-sensing.