高双折射光纤环镜改善40 GHz光时钟消光比的研究

时钟信号的好坏在同步、解复用和光判决中起着决定性的作用,双折射光纤环镜具有灵活可调的滤波特性,光时钟信号通过双折射环形镜可以使其消光比得到改善,从而提高时钟信号的质量。为此提出了利用高双折射光纤环形镜提高光时钟信号消光比的方案,数值上模拟了环形镜透射谱随双折射器件偏振延时量(Δt)、偏振控制器快慢轴角度以及偏振控制器所引入光程差的变化而变化的情况,并理论分析了消光比不理想的时钟信号经过环形镜后的光谱形式。用法布里-珀罗滤波器提取的40 GHz时钟信号进行实验,时钟经过环形镜后消光比改善了13 dB,实验结果和理论模拟得到了很好的匹配。

Improvement of Extinction Ratio of 40 GHz Optical Clock Using with High-Birefringence Fiber Loop Mirror

The quality of clock signal plays a key role in synchronization, demultiplexing and optical decision. The extinction ratio of optical clock signal can be greatly increased after passing through birefringent fiber loop mirror (FLM), due to its flexibly tunable filtering characteristics, and then the clock signal quality is improved. We propose a method of using high-birefringence fiber loop mirror to enhance the extinction ratio (ER), numerically simulate the transmission spectrum variation of birefringent fiber loop mirror by adjusting birefringence device' polarization delay, fast/slow axis angle and optical path difference of the polarization controller; and theoretically analyze the clock spectrum after it passes through birefringent fiber loop mirror with an unperfect extinction ratio. With a 40 GHz clock signal extracted by Fabry-Pérot filter as input, an experiment is performed. The result shows that the extinction ratio of the input clock is improved by 13 dB, which verifies the results of numerical simulation.