Polarization insensitive electro-optic probe using birefringence-free interferometric modulation

We report the fabrication and characterization of a sensitivity-stabilized fiber-optic probe for electric field sensing, which exhibits signal fluctuations of less than ±0.2  dB with any polarization state of the incident probe beam. The polarization instability issue in fiber-coupled sensors, which often occurs due to birefringence drift in lengthy optical fibers, can be well addressed with the proposed birefringence-free interferometric modulation scheme. The proposed fiber sensor could be an excellent solution for ultra-long remote sensing and for applications in which external physical disturbances of the probing fiber are a challenge.