Liquid seal for temperature sensing with fiber-optic refractometers

Area of Science:

• Fiber optics
• Optical sensing
• Material science

Background:

• Fiber-optic refractometers typically measure refractive index.
• Converting refractometers to temperature sensors often requires complex modifications.
• Existing fiber-optic temperature sensors have limitations in sensitivity and robustness.

Purpose of the Study:

• To develop a simple and highly sensitive fiber-optic temperature sensor.
• To investigate the feasibility of using liquid sealing to enhance temperature sensitivity.
• To analyze the sensing mechanisms and robustness of the liquid-sealed sensor.

Main Methods:

• A thin-core fiber modal interferometer was fabricated.
• The interferometer was sealed within a capillary tube using Cargille oil.
• Thermo-optic effects and temperature-induced strain were analyzed theoretically and experimentally.

Main Results:

• The liquid-sealed sensor exhibited a highest sensitivity of -2.30 nm/°C.
• This sensitivity is over 250 times higher than the intrinsic sensitivity of the refractometer.
• The sensor demonstrated robustness and insensitivity to surrounding refractive index changes.

Conclusions:

• Liquid sealing effectively converts fiber-optic refractometers into high-sensitivity temperature sensors.
• The technique is simple, low-cost, and enhances sensor performance significantly.
• This method holds potential for application in various fiber-optic sensing platforms.