Stabilisation of an optical fiber Michelson interferometer measurement system using a simple feedback circuit

Single-mode optical fiber interferometers used with fiber measurement systems must be stabilised to achieve high measurement accuracy and linearity in the presence of differential phase drift in their arms resulting from temperature fluctuations and other types of the environmental disturbances. By employing fiber Bragg gratings (FBGs) as in-fiber reflective mirrors, two interleaved fiber Michelson interferometers which share the common-interferometric-optical path are configurated. One of the fiber interferometers is used to stabilise the system while the other one is used to perform the measurement task. A simple electronic feedback loop for compensating the influences resulting from environmental disturbances is designed and the measurement system is stabilised. This makes the system suitable for on-line precision measurement.