The Characterization of Optical Fibers for Distributed Cryogenic Temperature Monitoring.

Area of Science:

• Materials Science
• Cryogenics
• Sensor Technology

Background:

• Optical fiber sensors offer unique advantages for monitoring superconducting devices at cryogenic temperatures.
• However, their thermal response becomes non-linear and diminishes below 50 K, necessitating detailed characterization.
• Special coatings can enhance fiber sensitivity at very low temperatures.

Purpose of the Study:

• To experimentally characterize the thermal response of optical fibers with various polymeric coatings from 5 K to 300 K.
• To assess the suitability of these fibers for cryogenic sensing applications, particularly for superconducting devices.
• To validate the accuracy of optical fiber temperature measurements against standard sensors in a cryogenic environment.

Main Methods:

• Experimental characterization of the thermal response of four optical fiber types (acrylate, polyimide, PEEK coatings) across a temperature range of 5 K to 300 K.
• Multiple consecutive thermal cycles were performed to ensure result reliability and estimate sample sensitivity.
• Validation of fiber performance by monitoring the cooldown of a superconducting link using acrylate and PEEK coated fibers.

Main Results:

• Detailed thermal response curves were obtained for each fiber coating type.
• The sensitivity of the fibers was accurately estimated across the cryogenic temperature range.
• Optical fiber temperature readings closely matched those from standard electronic sensors during superconducting link cooldown.

Conclusions:

• Optical fiber sensors with appropriate coatings demonstrate reliable performance for cryogenic temperature monitoring.
• The characterized thermal responses enable accurate temperature translation from optical readings.
• These sensors provide valuable insights into cryogenic system dynamics, such as superconducting link cooldown.