An Integrated OFDR System Using Combined Swept-Laser Linearization and Phase Error Compensation

This article describes a flexible, compact, semiconductor laser (SCL)-based optical frequency-domain reflectometry (OFDR) design, incorporating swept-laser linearization functions (both passive and active), in situ phase error evaluation function, and phase error compensation function. At the core of the proposed design, a fiber-optic Mach-Zehnder interferometer (MZI) and its electronic digitization components (photodetector and zero-cross circuit) simultaneously perform all the above mentioned functions. Benefitting from the unique digital design, this system combines all functions in a compact fashion without increasing complexity and overhead. Experimental results demonstrate enhanced accuracy using the integrated design compared with prior methods, as well as improved cost-effectiveness, reduced complexity, and optimized form factor.