Opt Lett. 2019 Mar 15;44(6):1331-1334. doi: 10.1364/OL.44.001331.
We propose and experimentally demonstrate a bidirectional radio-over-fiber (RoF) link based on a Sagnac loop incorporating a polarization modulator (PolM) to generate simultaneously a polarization-modulated optical signal and an unmodulated optical signal for wavelength reuse and for increasing the dynamic range. Thanks to the traveling-wave nature of the PolM, a polarization-modulated optical signal and an unmodulated optical signal are generated at the output of the Sagnac loop, which are combined at a polarizer and detected at a photodetector. By controlling the powers of the two optical signals, the third-order intermodulation distortion terms can be fully suppressed to increase the dynamic range for downstream transmission. The unmodulated optical signal is reused for upstream transmission. A bidirectional RoF link to transmit 2.5 Gb/s 16QAM downstream and upstream signals, and a 7.1 Gb/s 128 subcarrier orthogonal frequency division multiplexing 16QAM downstream and upstream signals using a single wavelength over a 10.5 km single-mode fiber are experimentally demonstrated. The transmission performance versus the dynamic range is also studied.
我们提出并实验演示了一种基于 Sagnac 环的双向无线电光纤（RoF）链路，该链路采用偏振调制器（PolM）来同时生成偏振调制光信号和未调制光信号，以实现波长重用和提高动态范围。由于 PolM 的行波特性，偏振调制光信号和未调制光信号在 Sagnac 环的输出端产生，这两个信号在偏振器处组合，并在光电探测器处检测。通过控制两个光信号的功率，可以完全抑制三阶互调失真项，从而提高下游传输的动态范围。未调制的光信号可用于上行传输。实验演示了一种双向 RoF 链路，可在 10.5km 单模光纤上使用单个波长传输 2.5Gb/s 16QAM 下行和上行信号，以及 7.1Gb/s 128 个副载波正交频分复用 16QAM 下行和上行信号。还研究了传输性能与动态范围的关系。
