Nonplanar fiber-optic sensing head for the compensation of bending-induced birefringence in Faraday current sensors.

We demonstrate the compensation of bending-induced linear birefringence in single-mode fibers coiled in a nonplanar path by alternating orthogonal bending planes. This effect can be applied for the construction of birefringence-free fiber coils in Faraday sensor heads (e.g., in current sensors) to improve their sensitivity. Validation experiments are presented.