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
$\,\times 10^{-5}~{\rm rad}/\surd{\rm Hz}$
, 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.