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针对空间扫描型多通道光纤Fabry-Perot(F-P)解调系统中LED输出光功率变化及通道间光功率损耗差异引起解调系统信噪比(SNR)下降进而影响解调精度的现象,提出一种基于差分滤波法评价SNR水平的快速LED输出光功率自适应调节方法,通过模拟调光方式使低相干干涉信号维持较高的SNR水平。搭建四通道光纤F-P压力解调系统进行实验研究,结果表明,本文方法可在0.36s之内恢复链路损耗突变造成的SNR波动;在5~150kPa压力范围内,最大压力解调误差为0.038kPa,解调精度优于0.03%(F.S.)(F.S.表示全量程),与以往固定光源功率方法相比,精度提高2.28倍以上;在102kPa下采用本文方法调节后的各通道SNR均优于26.5dB,有效提高了光功率变化情况下光纤F-P系统SNR及解调精度的稳定性。
Aiming at the phenomenon that the SNR of the demodulation system is degraded and the demodulation accuracy is affected by the variation of the output optical power of the LED and the optical power loss between the channels in the space-scanning multi-channel Fabry-Perot (FP) demodulation system, Based on the differential filtering method to evaluate the level of SNR, a fast LED output optical power adaptive adjustment method is adopted to maintain the low-coherent interference signal at a high SNR level through analog dimming. The experimental results show that this method can recover the SNR fluctuation caused by the sudden change of link loss within 0.36s and the maximum pressure demodulation error is 0.038kPa in the pressure range of 5 ~ 150kPa , The accuracy of demodulation is better than 0.03% (FS) (FS stands for the full range), which is 2.28 times higher than the conventional method of fixed light source power. The SNR of each channel adjusted by this method is better than 26.5dB at 102kPa , Which effectively improves the stability of SNR and demodulation accuracy of optical fiber FP system under the condition of optical power variation.