Numerical modeling of a novel athermal fiber optic cable

This paper introduces and numerically investigates a special optical fiber cable with zero temperature-induced phase shift. The cable structure consists of stacked layers of two materials with opportune mechanical, thermal, and geometrical properties. This structure allows adjusting the thermal-induced strain to the fiber, resulting in a broad tunability of the bare thermal expansion, including the negative range. By a proper choice of materials, the thickness of each layer, and the radius of the cable, the induced thermal strain can fully compensate for the thermo-optic effect, resulting in a complete temperature insensitivity of the phase shift. This cable may be of great interest in the sensing fields in all those applications where the temperature compensation is critical, such as in low-frequency distributed acoustic sensing. Moreover, it could be relevant for a wide range of telecom applications that require precise thermal control.