An Ameliorated Phase Generated Carrier Demodulation Algorithm With Low Harmonic Distortion and High Stability

• Published in: Journal of lightwave technology Vol. 28; no. 22; pp. 3258 - 3265
• Main Authors: He, Jun, Wang, Lin, Li, Fang, Liu, Yuliang
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 15.11.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithm design and analysis; Algorithms; Applied sciences; Carriers; Circuit properties; Demodulation; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Fiber-optic instruments; fiber-optic interferometer; fiber-optic sensor; Frequency modulation; Harmonic distortion; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Integrated optics. Optical fibers and wave guides; Interference; light intensity disturbance (LID); Noise levels; Nonlinearity; Optical and optoelectronic circuits; Optical instruments, equipment and techniques; Phase generated carrier (PGC); Physics; Signal to noise ratio; Stability; Stability analysis; Studies; Performance evaluation; Dynamic response; fiber-optic interferometer; Phase demodulation; Phase shift; Interferometer; fiber-optic sensor; light intensity disturbance (LID); Algorithm; Non linear phenomenon; Fiber optic sensors; Fiber optics; Phase generated carrier (PGC); Dual carrier modulation; Current mode; Linearity; Trigonometric function; Analytical method; Harmonic distortion; Miniaturization; Non linear effect; Minimum phase; Signal to noise and distortion ratio; stability
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2010.2081347

A novel ameliorated phase generated carrier (PGC) demodulation algorithm based on arctangent function and differential-self-multiplying (DSM) is proposed in this paper. The harmonic distortion due to nonlinearity and the stability with light intensity disturbance (LID) are investigated both theoretically and experimentally. The nonlinearity of the PGC demodulation algorithm has been analyzed and an analytical expression of the total-harmonic-distortion (THD) has been derived. Experimental results have confirmed the low harmonic distortion of the ameliorated PGC algorithm as expected by the theoretical analysis. Compared with the traditional PGC-arctan and PGC-DCM algorithm, the ameliorated PGC algorithm has a much lower THD as well as a better signal-to-noise-and-distortion (SINAD). A THD of below 0.1% and a SINAD of 60 dB have been achieved with PGC modulation depth (C value) ranges from 1.5 to 3.5 rad. The stability performance with LID has also been studied. The ameliorated PGC algorithm has a much higher stability than the PGC-DCM algorithm. It can keep stable operations with LID depth as large as 26.5 dB and LID frequency as high as 1 kHz. The system employing the ameliorated PGC demodulation algorithm has a minimum detectable phase shift of 5 μrad/√Hz @ 1 kHz, a large dynamic range of 120 dB @ 100 Hz, and a high linearity of better than 99.99%.