DC-offset-free homodyne interferometer and its nonlinearity compensation.

This study presents an analysis of the cyclic nonlinearity in the homodyne interferometer starting from the interference principle. We present the design for an enhanced homodyne interferometer without DC offset, for which the nonlinearity model will not be influenced by the intensity of the measurement beam. Our experimental results show that the enhanced interferometer can suppress the nonlinearity to less than 0.5 nm with a system calibration involving gain adjustment and phase-correction methods.