In this paper, a novel spectral-efficient coherent radio-over-fiber (RoF) link with linear digital phase demodulation is proposed and experimentally demonstrated. At the transmitter, to make an efficient use of the optical power and spectra, an intensity-modulated optical signal serving as the optical reference signal and a phase-modulated optical signal are polarization-multiplexed on a single optical carrier. At the receiver, the two optical signals are coherently detected with an optical local oscillator (OLO) and demodulated free of laser phase fluctuation through digital signal processing. Owing to simple and linear digital phase demodulation, an RF input signal is linearly demodulated from the optical phase without approximations and preconditions, which preserves the linearity of the phase-modulated RoF optical link from the transmitter end to the receiver end. The proposed scheme is experimentally verified by 25-km single-mode-fiber (SMF) transmission of two 16-QAM microwave vector signals at 2 GHz and 2.4 GHz, both with a symbol rate of 50 Msymbol/s. The transmission performance in term of error vector magnitude (EVM) is evaluated. Additionally, 25-km SMF transmission of the phase-modulated input signal with a spurious-free dynamic range (SFDR) of 112.8 dB·Hz2/3 is obtained.

中文翻译：

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一种具有线性数字相位解调的新型频谱高效相干光纤无线电链路

在本文中，提出并通过实验证明了一种具有线性数字相位解调的新型频谱效率相干光纤 (RoF) 链路。在发射机处，为了有效利用光功率和光谱，用作光参考信号的强度调制光信号和相位调制光信号在单个光载波上偏振复用。在接收器处，两个光信号通过光本地振荡器 (OLO) 进行相干检测，并通过数字信号处理进行无激光相位波动的解调。由于简单和线性的数字相位解调，RF 输入信号从光相位线性解调，无需近似和前提条件，这保留了从发射器端到接收器端的相位调制 RoF 光链路的线性度。所提出的方案通过 2 GHz 和 2.4 GHz 两个 16-QAM 微波矢量信号的 25 公里单模光纤 (SMF) 传输进行了实验验证，两者的符号速率均为 50 Msymbol/s。评估在误差矢量幅度 (EVM) 方面的传输性能。此外，还获得了具有 112.8 dB·Hz2/3 的无杂散动态范围 (SFDR) 的相位调制输入信号的 25 公里 SMF 传输。