Suppression of interference noise caused by Fresnel reflection in all-fiber white-light interferometer.

We propose methods to suppress the interference noise (IN) of an all-fiber white-light interferometer (WLI), which is caused by the residual Fresnel reflective beam. The methods are proposed to ensure a wide dynamic range and enhance the accuracy of measurement. IN can cause misjudgment of the realistic optical characteristic parameters, such as the fault diagnosis and polarization coupling of the optical devices under test. In addition, IN can reduce the dynamic range of the WLI. The optical path mismatch (OPM) method and the intensity suppression (IS) method by changing the positions and intensity of the IN are presented. The two suppression methods can successfully restrain IN caused by the Fresnel reflection beams. The experimental results show that IN is successfully suppressed by the OPM method or restrained by IS method in interferograms, and the dynamic range can achieve 85 dB without IN.