In this Letter, we experimentally demonstrate an unamplified analog RoF distribution of 60 GHz 5G signals. The system entails the heterodyning of two optical tones from an externally injected gain switched laser (EI-GSL) based optical frequency comb to generate a millimeter wave (mmW) signal. A fixed frequency separation and a high level of phase correlation, between the EI-GSL comb lines, results in the generation of a high-quality signal. An active demultiplexer is used to filter and amplify two comb tones, thus alleviating the need for an external optical amplifier to boost the low power comb tones. Furthermore, the same demultiplexer is also used to modulate one of the tones with a 64-QAM UF-OFDM signal. Such an approach enables the remote generation of a mmW downlink data signal as well as an unmodulated RF carrier that could be used to downconvert the mmW signals to an intermediate frequency. Using the abovementioned scheme, we demonstrate the distribution of the downlink signal over 25 km of fiber, achieving a BER of ${2.4{\rm e} - 3}$ (below the HD-FEC limit of ${3.8{\rm e} - 3}$) and only a 0.5 dB penalty at the FEC limit in comparison to the BtB case.

中文翻译：

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有源解复用器支持直接调制的64-QAM UF-OFDM信号的mmW ARoF传输。

在这封信中，我们通过实验证明了60 GHz 5G信号的未经放大的模拟RoF分布。该系统需要来自基于外部注入的增益开关激光器（EI-GSL）的光学频率梳的两个光学色调的异质化，以生成毫米波（mmW）信号。EI-GSL梳状线之间固定的频率间隔和高水平的相位相关性导致生成高质量信号。有源解复用器用于滤波和放大两个梳齿音，因此无需外部光学放大器来提升低功率梳齿音。此外，同一解复用器也用于调制具有64-QAM UF-OFDM信号的音频之一。这样的方法使得能够远程生成mmW下行链路数据信号以及可用于将mmW信号下变频为中频的未调制的RF载波。使用上述方案，我们演示了下行链路信号在25 km光纤上的分布，实现了BER的$ {2.4 {\ rm e}-3} $（低于$ {3.8 {\ rm e}-3} $的HD-FEC限制），与BtB情况相比，FEC限制只有0.5 dB的损失。