PAM4 Transmission Over OM3 Fiber Using OAM Mode Group Multiplexing

This paper investigates the bit error rate (BER) performance of the 10 Gbaud PAM4 transmission over conven- tional multimode fiber using OAM mode group multiplexing. This proof-of-concept study uses two orbital angular momentum (OAM) mode groups, with topological charges l = 0, and l =  + 1, without using any multiple-input-multiple-output (MIMO) processing. The study reveals that the 10 Gbaud PAM4 transmissions are possible using OAM mode multiplexing over 1 km conventional Multimode fiber with some stability challenges. Moreover, we have found that each mode achieved the bit error rate value well below the pre-FEC 3.8 × 10−3 after 1 km of OM3 fiber. This study also reports the open eye diagrams, which are captured over several minutes, indicating that PAM4 transmission is possible over conventional fiber. This study also emphasizes that a proper adaptive polarization adjustment is required to achieve long-term stability in terms of reduced crosstalk.