Optical fiber interferometer has been developed for over a hundred years and is used as precision metrology that is widely used in the optical system for extremely accurate measurements for a variety of physical quantities in laboratories as well as in industry fields. The base of optical interferometry technology lies in the interference of light beams that are launched from another monochromatic source, same light source, or laser source. It propagates through space or dielectric mediums such as glass waveguides with different optical paths. It then arrives simultaneously at a point in space or on the surface of an object. Hence the light intensity will differ periodically with the optical path difference, which is the optical phase difference, between the beams. This is a much known process of light interference.

In the wavelength scale of the optical light source, a very small change in the optical path difference can induce an obvious and measurable change in the intensity of the interference light. So, by measuring the changes of interference light intensity, one can obtain information regarding the changes of optical paths in an optical measurement system. The optical interferometer is built as an instrument due to this mechanism and for accurate measurements of many physical quantities, such as the displacement, velocity, and distance, as well as for tests of optical systems it is widely used.

Optical interferometry technology has made great progress due to huge developments of laser and fiber optic technologies and has also evolved from classical bulk optics to fiber optics. Applications of the optical interferometers have been expanded to areas such as underwater acoustic detections, voltage and current measurements inside electric power systems, and biomedical pressure monitoring in living bodies but everything depends on fiber-optic technologies.

One major application of the optical interferometer is that it is used as the optical interferometer sensor for the detection of unknown and uncontrolled physical parameters. Fiber-optic-based interferometers use optical fibers as sensor light carriers. From fiber-connected transducers or directly from fibers it obtains the detection information.

In general, the preparation of optical power meter and fiber-optic transducers/sensors is done from totally dielectric materials that are chemically inert and completely immune to electromagnetic interference (EMI).