10 August 2015 An improved fixed phased demodulation method combined with phase generated carrier (PGC) and ellipse fitting algorithm
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Proceedings Volume 9620, 2015 International Conference on Optical Instruments and Technology: Optical Sensors and Applications; 96200S (2015) https://doi.org/10.1117/12.2190842
Event: International Conference on Optical Instruments and Technology 2015, 2015, Beijing, China
Abstract
In this paper, we present an improved fixed phased demodulation method combined with phase generated carrier (PGC) and ellipse fitting algorithm (EFA) to enhance the phase resolution and suppress the total harmonic distortion (THD) caused by the laser intensity disturbance (LID) of modulation phase. We make the subtraction operation to the outputs of the two 1×2 couplers to get the differential signals without DC offset, which is used to achieve the fixed phase demodulation. The EFA is applied to construct the standard quadrature signals with the two signals. The last output is utilized to finish the small amplitude (<2π rad) demodulation in PGC method, which can increase the phase resolution. The distortion signals caused by the LID effect can be eliminated by the EFA. According to the result, the phase error of the EFA is 0.03rad, the amplitude error is 5% and the phase resolution of system is 2.0×10-6rad/√Hz@1kHz (-106.3dB) with the THD is 5%.
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Feng Peng, Lu Hou, Jun Yang, Yonggui Yuan, Chuang Li, Dekai Yan, Libo Yuan, Hui Zheng, Zheng Chang, Kun Ma, Jiyong Yang, "An improved fixed phased demodulation method combined with phase generated carrier (PGC) and ellipse fitting algorithm", Proc. SPIE 9620, 2015 International Conference on Optical Instruments and Technology: Optical Sensors and Applications, 96200S (10 August 2015); doi: 10.1117/12.2190842; https://doi.org/10.1117/12.2190842
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