In this paper, an integrated compact four-channel directly modulated analog optical transceiver is proposed and fabricated. The 3 dB bandwidth of this optical transceiver exceeds 20 GHz, and the measured spurious-free dynamic range is up to 91.2 dB·Hz2/3. The optical coupling efficiency (CE) is improved by using a precise submicron alignment technique for lens coupling in a transmitter optical subassembly, and the highest CE is achieved when the oblique angle of the arrayed waveguide grating using a silica-based planar lightwave circuit (AWG-PLC) in receiver optical sub assembly is set to 42°. Based on the proposed optical transceiver, we have experimentally demonstrated a 6.624 Gbit/s 4×4 multi-input multioutput (MIMO) 16-quadrature amplitude modulation orthogonal frequency division multiplexing (16QAM-OFDM) radio signal over 15.5 km standard single mode fiber, together with 1.2 m wireless transmission in both an uplink and a downlink. To cope with the channel interference and noise of the fiber-wireless transmission system, a low-complexity MIMO demodulation algorithm based on lattice reduction zero-forcing (LR-ZF) is designed. In our experiment, 1.6 dB power penalty is achieved by using the proposed LR-ZF algorithm, compared to the commonly used zero-forcing algorithm. Moreover, this LR-ZF algorithm has much less complexity than the optimal maximum-likelihood sequence estimation (MLSE) at a given transmission performance. These results not only demonstrate the feasibility of the integrated optical transceiver for MIMO fiber-wireless application but also validate that the proposed LR-ZF algorithm is effective to eliminate the interference for hybrid fiber-wireless transmission.

中文翻译：

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基于集成四通道直接调制光收发器的4×4 MIMO光纤无线传输

在本文中，提出并制造了一种集成的紧凑型四通道直接调制模拟光收发器。该光模块的3dB带宽超过20GHz，实测无杂散动态范围高达91.2dB·Hz2/3。通过在发射器光学组件中使用精确的亚微米对准技术进行透镜耦合，提高了光耦合效率（CE），当阵列波导光栅的斜角使用基于二氧化硅的平面光波电路（AWG）时，可实现最高的 CE -PLC) 在接收器光学子组件中设置为 42°。基于所提出的光收发器，我们通过实验证明了 6.624 Gbit/s 4×4 多输入多输出 (MIMO) 16 正交调幅正交频分复用 (16QAM-OFDM) 无线电信号超过 15。5 公里标准单模光纤，以及 1.2 米的上行和下行无线传输。针对光纤无线传输系统的信道干扰和噪声问题，设计了一种基于格约化迫零(LR-ZF)的低复杂度MIMO解调算法。在我们的实验中，与常用的迫零算法相比，使用所提出的 LR-ZF 算法实现了 1.6 dB 的功率损失。此外，在给定的传输性能下，这种 LR-ZF 算法的复杂性远低于最佳最大似然序列估计 (MLSE)。