A Taper-in-Taper Structured Interferometric Optical Fiber Sensor for Cu²⁺ ion Detection

Area of Science:

• Fiber optic sensing
• Environmental monitoring
• Analytical chemistry

Background:

• Copper ions (Cu²⁺) in drinking water pose health risks.
• Existing detection methods lack sensitivity, reliability, and cost-effectiveness.
• Electromagnetic interference is a challenge for current devices.

Purpose of the Study:

• To develop a highly sensitive, reliable, and cost-effective fiber optic sensor for Cu²⁺ detection.
• To overcome limitations of existing copper ion sensors.
• To create an electromagnetic-interference-immune device for drinking water analysis.

Main Methods:

• Fabrication of a taper-in-taper fiber sensor using mode-mode interference.
• Deposition of polyelectrolyte layers for enhanced Cu²⁺ detection.
• Utilizing a novel secondary taper structure formed by two-arc discharge in single-mode fiber.

Main Results:

• The sensor achieved a refractive index (RI) sensitivity of 2741 nm/RIU, 3.7 times higher than traditional tapered sensors.
• Sensitivity for Cu²⁺ detection reached 78.03 nm/mM within the 0-0.1 mM concentration range.
• The taper-in-taper fiber sensor demonstrated high sensitivity, good stability, and mechanical strength.

Conclusions:

• The developed taper-in-taper fiber sensor is a promising tool for detecting low concentrations of Cu²⁺ in drinking water.
• The sensor design offers significant sensitivity enhancement and overcomes electromagnetic interference issues.
• This technology has potential applications in environmental and health monitoring systems.