Time-domain Measurement and Analysis of Differential Mode Delay and Modal Bandwidth of Graded-Index Multimode Fiber in SDM Networks

Abstract

Abstract A novel differential mode delay (DMD) and modal bandwidth measurement technique for a multi-mode optical fiber based on time-domain method has been proposed and analyzed. Mode-dependent loss (MDL) is known to have a detrimental impact on the capacity of multi-mode fiber systems. The bandwidth behavior of 50 μm/62.5 μm graded-index multimode fibers (GI-MMFs) is investigated by launching a temporal pulse into the fiber and measuring the output time-domain waveform to understand and characterize the effect of DMD. The baseband response is measured by observing the broadening of a narrow input pulse (time-domain measurement). This paper verifies the degradation in bandwidth due to profile distortion by the maximum radial shift (starting from the center of the fiber) and the number of steps. The impact due to DMD on GI-MMF performance has been analyzed through fiber transfer function, pulse width and phase changes.