Millimeter Resolution Otpical Reflectometry Over Up to Two Kilometers of Fiber Length

In recent years, optical frequency domain reflectometry (OFDR) has emerged as an effective measurement technique for characterizing short-haul optical networks such as those used in avionics. Comparable techniques such as optical time domain reflectometry (OTDR) and optical low coherence reflectometry (OLCR) are restricted in either spatial resolution or distance range respectively compared to OFDR. Earlier papers have shown OFDR measurements over up to 500 m in length (Soler et al., 2005). In this work, the authors demonstrate OFDR measurements over two kilometers of fiber length with millimeter level spatial resolution. The data required for this measurement was acquired in less than 100 ms and results in a sensitivity of over 130 dB. This level of measurement performance enables unprecedented visibility into fiber-optic networks. In addition, OFDR can be used for distributed fiber sensing of temperature and strain. The authors demonstrate distributed temperature sensing up to 800 degC. The paper also show distributed strain measurements at a distance of 800 m with cm level spatial resolution. These link characterization and sensing capabilities of OFDR make the technique particularly well suited for test and trouble-shooting in avionics applications.