Azimuth-Rotated Splicings of a Four-Core Optical Fiber for Inter-Core Group Delay Compensation

This letter presents an experimental method to compensate for the differential group delay between the core modes in a multi-core fiber. Optical fiber sections are sequentially spliced with azimuthal offsets such that light initially launched to any cores can propagate through the combination of the same lengths of different cores, resulting in ideally uniform group delay. The differential group delays before and after the compensation are measured by wavelength-domain Mach-Zehnder interferometry through multi-core fiber sections. The experimental results show that the group delay compensation is practically limited by non-uniformity of the multi-core fiber.