Nonlinearity detection of laser frequency tuning for improving spatial resolution in OFDR

Abstract

High spatial resolution is one of the main requirements in Optical Frequency Domain Reflectometry (OFDR) system. Swept tuning in laser system which has been widely used in OFDR system is not linear. This nonlinearity can reduce spatial resolution in OFDR system. In this paper, we present a simple signal processing technique for detecting laser nonlinearity tuning in OFDR system. Information about laser nonlinearity which is previously detected will be used for resampling the reflection data from OFDR. The resampling process is used for compensating the existence of nonlinearity. By using this technique, we obtain fifth times resolution enhancement and 0.02 spatial resolution ratio. Moreover, our system is able to detect nonlinearity in laser tuning which takes around 2 seconds of data processing time.