Wei Xuhao, Numkam Fokoua Eric, Poletti Francesco, Slavík Radan
Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, U.K.
Microsoft U.K., Romsey SO51 9DL, U.K.
ACS Photonics. 2024 Sep 24;11(10):4076-4082. doi: 10.1021/acsphotonics.4c00859. eCollection 2024 Oct 16.
Optical time domain reflectometry (OTDR) is a key technique to characterize fabricated and installed optical fibers. It is also widely used in distributed sensing. OTDR of emerging hollow-core fibers (HCFs) has been demonstrated only very recently, being almost 30 dB weaker than that in the glass-core optical fibers. However, it has been challenging to extract useful data from the OTDR traces of HCFs, as the longitudinal variation in the fiber's geometry, notably the core size or the longitudinal variations of the air pressure within the core, results in commensurate changes of the backscattering strength. This is, however, necessary for continuous improvement of HCF fabrication and subsequent improvement in their performance such as minimum achievable loss, potentially enabling the use of HCF in a significantly broader range of applications than used today. Here, we demonstrate, for the first time, that the distributed loss and backscattering coefficient in antiresonant HCFs can be separated, obtaining key data about fiber distributed loss and uniformity. This is enabled by using OTDR traces obtained from both ends of the HCF.
光时域反射仪（OTDR）是表征预制和已安装光纤的一项关键技术。它也广泛应用于分布式传感。新兴的空心光纤（HCF）的OTDR直到最近才得到证明，其强度比玻璃芯光纤中的OTDR弱近30 dB。然而，从HCF的OTDR迹线中提取有用数据一直具有挑战性，因为光纤几何结构的纵向变化，特别是芯尺寸或芯内气压的纵向变化，会导致后向散射强度发生相应变化。然而，这对于持续改进HCF制造工艺以及随后改善其性能（如最小可实现损耗）是必要的，这有可能使HCF在比目前使用的范围更广得多的应用中得到使用。在此，我们首次证明，可以分离反谐振HCF中的分布式损耗和后向散射系数，从而获得有关光纤分布式损耗和均匀性的关键数据。这是通过使用从HCF两端获得的OTDR迹线实现的。
