In-line Sagnac interferometer current sensor

Optical Current Sensors for High Power Systems: A Review

“…This phase carrier can be generated by using an unbalanced Michelson or Mach-Zehnder interferometer, or other interferometric configuration, such as Sagnac interferometer [1,3]. Figure 5 shows schematically a current sensing Sagnac interferometer, which is commonly used in gyroscopes and it is sensitive to non-reciprocal effects [4]. This interferometer is interrogated by using a heterodyne detection scheme.…”

“…Although the two schemes described permit a certain degree of immunity to reciprocal perturbations, timevarying disturbances which alter the birefringence of the PM fiber, affect counter-propagating waves differently and are not compensated [4]. Also, the fact that we are working with interferometers, means that it is necessary to use a stable optical source, and the modulation despite granting certain immunity to low frequency noise, limiting the system bandwidth.…”

Resonantly enhanced Faraday rotation in a microcoil current sensor

“…iber-optic current sensors that exploit the Faraday Effect [1][2][3] have attracted a great deal of interest due to their wide dynamic range, robustness and remote sensing capability. However, those based on conventional optical fiber have been relatively bulky due to the requirement of satisfying minimum fiber bend radius criteria.…”

Optical fiber current sensors in high electric field environments

“…The response function of a loop Sagnac current sensor is [37], [38] (6) where loop is the measured phase shift in the interferometer. An in-line Sagnac current sensor has a similar response except that - [37]. Fig.…”