Compensation of Multimode Fiber Dispersion by Optimization of Launched Amplitude, Phase, and Polarization

In previous work, a technique was proposed for compensation of modal dispersion in multimode fiber (MMF) systems by using adaptive optics. A spatial light modulator (SLM), with amplitude and phase adjustable over discrete blocks, was used to control the field launched into a MMF. The system impulse response was found as a function of the SLM settings and the field patterns of the MMF principal modes, which were assumed to be known. Using principles of convex optimization, an optimal solution for the SLM settings was obtained, which minimizes intersymbol interference (ISI) subject to physical constraints. Here, we extend the previous method to include control over launched polarization. We propose five adaptive optics configurations, some permitting control only of overall polarization, and others permitting block-wise polarization control. For each configuration, we find optimal adaptive optics settings, which minimize ISI. We show that the best performance is obtained by two configurations that permit independent block-wise control of amplitude, phase and polarization.