Ren Yongxiong, Wang Zhe, Liao Peicheng, Li Long, Xie Guodong, Huang Hao, Zhao Zhe, Yan Yan, Ahmed Nisar, Willner Asher, Lavery Martin P J, Ashrafi Nima, Ashrafi Solyman, Bock Robert, Tur Moshe, Djordjevic Ivan B, Neifeld Mark A, Willner Alan E
Opt Lett. 2016 Feb 1;41(3):622-5. doi: 10.1364/OL.41.000622.
We experimentally demonstrate and characterize the performance of a 400-Gbit/s orbital angular momentum (OAM) multiplexed free-space optical link over 120 m on the roof of a building. Four OAM beams, each carrying a 100-Gbit/s quadrature-phase-shift-keyed channel are multiplexed and transmitted. We investigate the influence of channel impairments on the received power, intermodal crosstalk among channels, and system power penalties. Without laser tracking and compensation systems, the measured received power and crosstalk among OAM channels fluctuate by 4.5 dB and 5 dB, respectively, over 180 s. For a beam displacement of 2 mm that corresponds to a pointing error less than 16.7 μrad, the link bit error rates are below the forward error correction threshold of 3.8×10(-3) for all channels. Both experimental and simulation results show that power penalties increase rapidly when the displacement increases.
我们通过实验演示并表征了在建筑物屋顶上120米距离的400吉比特每秒轨道角动量（OAM）复用自由空间光链路的性能。四个OAM光束，每个承载一个100吉比特每秒的正交相移键控通道，进行复用并传输。我们研究了信道损伤对接收功率、通道间的模间串扰以及系统功率代价的影响。在没有激光跟踪和补偿系统的情况下，在180秒内，测量得到的OAM通道间的接收功率和串扰分别波动4.5分贝和5分贝。对于对应指向误差小于16.7微弧度的2毫米光束位移，所有通道的链路误码率均低于3.8×10(-3)的前向纠错阈值。实验和仿真结果均表明，当位移增加时，功率代价会迅速增加。
