Tseng Wen-Hung, Feng Kai-Ming
Institute of Photonics Technologies, National Tsing Hua University, HsinChu, Taiwan.
Opt Express. 2012 Jan 16;20(2):1597-607. doi: 10.1364/OE.20.001597.
Optoelectronic oscillators (OEOs), based on optical fiber loops to act as a high-Q cavity, are capable of generating stable radio-frequencies (RF). The long-term frequency stability of the OEO is then limited by the cavity variation that is mainly induced by temperature sensitivity of the optical fiber. In order to actively stabilize the OEO cavity, we employ the technique of RF transfer over optical fibers. We propose and experimentally demonstrate a dual-loop-OEO scheme to enhance the long-term stability with an injected probe signal to monitor the phase variation in the fiber loops. The experimental results show that the resulting spread-spectrum signal is useful in monitoring the fiber delay without observable interference. The relationships between the measured frequency and the monitored delay are theoretically and numerically discussed. We also estimate the long-term stability of the proposed OEO scheme with the cavity phase correction. The corrected result shows the long-term frequency stability of the proposed OEO is within 8.4×10(-8) at one day.
基于光纤环作为高Q腔的光电振荡器（OEO）能够产生稳定的射频（RF）。OEO的长期频率稳定性随后受到腔变化的限制，这种变化主要由光纤的温度敏感性引起。为了主动稳定OEO腔，我们采用了通过光纤进行射频传输的技术。我们提出并通过实验证明了一种双环OEO方案，通过注入探测信号来监测光纤环中的相位变化，以提高长期稳定性。实验结果表明，所得的扩频信号可用于监测光纤延迟，且无明显干扰。从理论和数值上讨论了测量频率与监测延迟之间的关系。我们还通过腔相位校正估计了所提出的OEO方案的长期稳定性。校正结果表明，所提出的OEO的长期频率稳定性在一天内为8.4×10(-8)以内。
