Fiber Bragg grating (FBG) array, consisting of a number of sensing units in a single optical fiber, can be practically applied in quasi-distributed sensing networks. Serious signal crosstalk occurring between large-serial of identical FBGs, however, has limited the further increase in the number of sensing units, thus restricting applications only for short-distance sensing networks. To reduce the signal crosstalk, we design two novel types of 10-kilometer-long FBG arrays with 10 000 equally spaced gratings, written on-line using a customized grating inscription system, which is affiliated to a drawing tower. Main factors causing signal crosstalk, such as spectral shadowing and multiple reflections, are firstly investigated in theory. Consistent with the theoretical findings, experimental results are proving that ultra-weak (the reflectivity of ∼−40 dB) and multi-wavelength gratings of a number more than 10 000 can be readily identified, with satisfied low crosstalk. The maximum attenuation of grating signal and minimum signal-to-noise ratio (SNR) in a single-wavelength array are 10.69 dB and 5.62 dB, respectively. As a comparison, by increasing the number of central wavelengths to three, the attenuation can be effectively reduced to 5.54 dB and the minimum SNR has been improved to 8.14 dB. The current study significantly enhances the multiplexing capacity of FBG arrays and demonstrates promising potentials for establishing large-capacity quasi-distributed sensing networks.

光纤布拉格光栅（FBG）阵列由单根光纤中的多个传感单元组成，可实际应用于准分布式传感网络。然而，大串联相同FBG之间发生的严重信号串扰限制了传感单元数量的进一步增加，从而限制了仅适用于短距离传感网络的应用。为了减少信号串扰，我们设计了两种新型 10 公里长的 FBG 阵列，具有 10 000 个等距光栅，使用定制的光栅铭文系统在线编写，该系统隶属于绘图塔。首先从理论上研究了引起信号串扰的主要因素，如光谱阴影和多次反射。与理论研究结果一致，实验结果证明，超弱（~-40 dB 的反射率）和数量超过 10 000 的多波长光栅可以很容易地识别出来，并且具有令人满意的低串扰。单波长阵列中光栅信号的最大衰减和最小信噪比（SNR）分别为10.69 dB和5.62 dB。相比之下，通过将中心波长增加到三个，衰减可以有效降低到5.54 dB，最小SNR提高到8.14 dB。目前的研究显着提高了 FBG 阵列的复用能力，并展示了建立大容量准分布式传感网络的潜力。单波长阵列中光栅信号的最大衰减和最小信噪比（SNR）分别为10.69 dB和5.62 dB。相比之下，通过将中心波长增加到三个，衰减可以有效降低到5.54 dB，最小SNR提高到8.14 dB。目前的研究显着提高了 FBG 阵列的复用能力，并展示了建立大容量准分布式传感网络的潜力。单波长阵列中光栅信号的最大衰减和最小信噪比（SNR）分别为10.69 dB和5.62 dB。相比之下，通过将中心波长增加到三个，衰减可以有效降低到5.54 dB，最小SNR提高到8.14 dB。目前的研究显着提高了 FBG 阵列的复用能力，并展示了建立大容量准分布式传感网络的潜力。