Radio over free space optics (Ro-FSO) systems have previously relied on the signal intensity, wavelength and polarization for multiplexing data streams in order to increase to the signal quality and achievable link range. This work leverages on optical space division multiplexing by using novel three-core photonic crystal fiber (PCF) mode group multiplexers and hexagonal mid-gapped tiered PCF mode group equalizers for improving the signal quality and increasing the achievable link range in a rural environment. At the transmitter, a three-core PCF mode group demultiplexer converts the fundamental mode into three distinct mode groups used as carriers for independent transmission of three radio frequency signals. At the receiver, the three PCF successfully equalizes the power from the received signal, with the channel impulse responses showing an improvement in the signal quality. An increment between 13.6% and 31.1% in the achievable link range for all channels is evident under medium and heavy fog conditions at the same bit error rate level, using the designed PCF mode group multiplexers and equalizers.

自由空间光学无线电（Ro-FSO）系统以前依靠信号强度，波长和偏振来复用数据流，以提高信号质量和可达到的链路范围。这项工作通过使用新颖的三芯光子晶体光纤（PCF）模式组多路复用器和六角形中间带隙分层PCF模式组均衡器来利用光空分复用，以改善信号质量并增加农村环境中可达到的链路范围。在发射机处，三核PCF模式组多路分解器将基本模式转换为三个不同的模式组，用作独立传输三个射频信号的载波。在接收器处，三个PCF成功地均衡了接收信号的功率，信道脉冲响应显示出信号质量的改善。使用设计的PCF模式组多路复用器和均衡器，在中等和重雾条件下，在相同的误码率水平下，所有通道可实现的链路范围内的增量明显在13.6％和31.1％之间。