Propagating data without MIMO over a weakly-coupled OAM fiber by multiplexing OAM mode group

Abstract

Urged by the continually increasing requirement of channel capacity, orbital angular momentum (OAM) has become a promising candidate for extending the multiplexed physical domain, which is compatible with the traditional physical space. However, due to the serious crosstalk among OAM modes and propagation loss, the OAM-based optical fiber communication (OFC) is limited within a shorter scope. A common multiple-input-multiple-out (MIMO) algorithm are usually employed to equalize the multiplexed channels for reducing the crosstalk at the cost of inevitably increasing the complexity of the system. For overcoming the aforementioned issues, a weakly-coupled OAM fiber (WCOF) is designed and manufactured to propagate OAM beams without MIMO, where three OAM mode groups (OMGs) are employed for multiplexing. An experimental setup is also designed and established for validating the feasibility of the proposed WCOF. The captured intensity profiles demonstrate the transmitted OAM beams can be successfully received, and the measured bit-error-rate (BER) distributions show the simulated user data carried by each of three OMGs can be correctly received with/without MDM after the propagation of more than 100 km WCOF when the received power (RP) is set to be greater than −28.33/-27.5 dBm, respectively. Moreover, the measured BERs of OMG1/2/3 are all below the Hard FEC threshold at the C + L waveband, which demonstrates that the proposed scheme can be utilized in the whole C + L waveband. In addition, the influences of data velocity and WCOF length on the BER are also exploded, which shows that the detected BER performance declines mildly as the data velocity increases from 10 to 40 Gbit/s, and the measured BER performance also slightly degrades as the WCOF length increases from 100 to 140 km. Therefore, the proposed scheme can be potentially utilized without MIMO for long-haul OFC with higher channel capacity.