PGC Demodulation Technique With High Stability and Low Harmonic Distortion

In the field of interferometric fiber-optic sensing, the differential-cross-multiplication type of phase-generated carrier (PGC) demodulation technique has a low stability defect and the arc tangent PGC demodulation technique has a high harmonic distortion defect. Thus, we present an improved PGC demodulation technique based on arc cotangent function and differential-self-multiplying. Both theoretical and experimental results show that the interferometric fiber-optic sensing system that has adopted the improved PGC demodulation technique has the merits of high stability of resisting the rapid change of light intensity and low harmonic distortion; experimental results show that the demodulation system has a resolution of 2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">\,× 10⁻⁵~ rad/ Hz</tex></formula> , a total harmonic distortion less than 0.1%, a linearity of better than 0.9999, and a dynamic range of 112 dB at 50 Hz.