Dissimilar cores in multicore optical fiber for strain and temperature separation

A method for calibrating an optical fiber having multiple first cores and one or more second cores, the multiple first cores having a first doping and a first thermal response, the one or more second cores having a second doping different from the first doping and a second thermal response different from the first thermal response, the method comprising:

• placing the optical fiber at least partially in a heated or a cooled environment having a temperature different from a surrounding environment, the surround environment surrounding the heated or cooled environment;
• straining the optical fiber to varying known strain levels at different temperatures,
• recording changes in length of the optical fiber for each of the known strain levels and for each of the different temperatures, and
• determining calibration parameters for the optical fiber by comparing the recorded changes in length for the optical fiber against previously recorded changes in length, the previously recorded changes in length for another optical fiber having only a set of cores having the first doping and no set of cores having the second doping.

An interferometric measurement system for measuring an optical fiber, the optical fiber including multiple first cores having a first thermal response and one or more second cores having a second thermal response, the first thermal response differing from the second thermal response, the system comprising:

• interferometric detection circuitry configured to detect measurement interferometric pattern data associated with each of the multiple first cores and each of the one or more second cores when the optical fiber is placed into a sensing position;
• data processing circuitry configured to determine compensation parameters based on the detected measurement interferometric pattern data, the compensation parameters for compensating for variations between a calibration configuration of the multiple first cores and the one or more second cores and an actual configuration of the multiple first cores and the one or more second cores, the compensation parameters including a temperature compensation parameter to compensate for temperature differences;
• and
• a memory configured to store the compensation parameters for compensating subsequently-obtained measurement interferometric pattern data for the optical fiber.