Sensitive liquid refractive index sensors using tapered optical fiber tips

Area of Science:

• Photonics and optical sensing
• Nanotechnology
• Chemical sensing

Background:

• Optical fiber sensors offer advantages in miniaturization and remote sensing.
• Subwavelength structures enable unique light-matter interactions for enhanced sensing capabilities.

Purpose of the Study:

• To develop and demonstrate a novel optical fiber sensor based on optical confinement changes in a subwavelength tip.
• To achieve high sensitivity for refractive index (RI) measurements.
• To showcase the sensor's application in real-time chemical analysis.

Main Methods:

• Fabrication of an optical fiber sensor with a subwavelength tip.
• Measurement of optical spot changes in response to environmental RI variations.
• Analysis of low angular spectral components for intensity sensitivity calculation.

Main Results:

• A substantial increase in the optical spot size was observed as RI increased from 1.3 to 1.4.
• An intensity sensitivity of up to 8000% per RI unit was achieved.
• The sensor demonstrated real-time measurement of acid concentrations and evaporation rates of aqueous mixtures.

Conclusions:

• The developed subwavelength fiber tip sensor provides a highly sensitive platform for RI sensing.
• The sensor's small detection volume and real-time response are advantageous for various chemical sensing applications.
• This technology holds promise for precise monitoring in chemical processes and environmental studies.