Opt Lett. 2018 Jun 1;43(11):2430-2433. doi: 10.1364/OL.43.002430.
A high-speed demodulation technique based on microwave photonics and chromatic dispersion is proposed for distributed weak fiber Bragg gratings (FBGs). A broadband light modulated with a frequency-swept microwave is reflected by FBGs, and the reflected signal mixes with the original microwave to produce a beat frequency. A dispersion compensation fiber (DCF) changes the beat frequency within the FBG wavelength range. With a crossing microwave sweep, all wavelengths of cascade FBGs can be quickly decoded by measuring the change of the beat frequency. The Chirp-Z + Hanning window algorithm helps to analyze the beat frequency in a single cycle. By adopting the single-peak filter as a reference, the DCF thermal drift can be also eliminated. Therefore, the wavelength detection accuracy is improved, and a higher demodulation speed of 40 kHz can be realized. We have demonstrated 105 FBGs with 0.1% reflectivity and 1 m interval, with the achieved accuracy of 8 pm.
提出了一种基于微波光子学和色度色散的高速解调技术，用于分布式弱光纤布拉格光栅（FBG）。宽带光通过扫频微波进行调制，被 FBG 反射，反射信号与原始微波混合产生拍频。色散补偿光纤（DCF）改变 FBG 波长范围内的拍频。通过交叉微波扫描，通过测量拍频的变化，可以快速解码级联 FBG 的所有波长。Chirp-Z+Hanning 窗口算法有助于在单个周期内分析拍频。通过采用单峰滤波器作为参考，可以消除 DCF 热漂移。因此，提高了波长检测精度，实现了 40 kHz 的更高解调速度。我们已经演示了具有 0.1%反射率和 1 m 间隔的 105 个 FBG，实现了 8 pm 的精度。
