As coherent reception technology continues to move downstream the optical telecommunication infrastructure, the complexity of the involved transceiver technology can quickly introduce a techno-economic roadblock. Under this umbrella, we experimentally demonstrate a conceptually simple, single-polarization and analogue coherent homodyne receiver that builds on no more than an optically locked externally modulated laser. We evaluate this coherent homodyne receiver in the context of analogue radio-over-fiber transmission – a demanding application setting, where a small degradation in signal integrity is leading to large reception penalties. We conduct a continuous-mode characterization of the locking methodology, which enables homodyne detection and hence the transparent translation of electrical signals from the optical to the electrical domain during the coherent reception process. Furthermore, the locking dynamics are being investigated for packet-level reception at a 1 MHz frame rate and two time division multiplexed channels, which are sourced by two optical emitters with free-running laser sources. The radio-over-fiber transmission performance is evaluated for 64-ary quadrature amplitude modulated, orthogonal frequency division multiplexed radio with a short guard interval of 2.7 μs between the packet radio signals. A data rate of 0.5 Gb/s over 100 MHz radio bandwidth is obtained at an optical loss budget of >35 dB between transmitter and receiver, without resorting to digital signal processing resources for the purpose of signal recovery. Moreover, a small ∼0.3% penalty in error vector magnitude between continuous- and packet-mode confirms the compatibility of the analogue coherent receiver in networks with fast locking requirements.

中文翻译：

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具有快速锁定至自由运行光发射器的模拟相干 TDMA 接收器

随着相干接收技术继续向光通信基础设施的下游移动，所涉及的收发器技术的复杂性很快就会成为技术经济障碍。在这把伞下，我们通过实验证明了一个概念上简单的、单偏振和模拟相干零差接收器，它只建立在一个光学锁定的外部调制激光器上。我们在模拟光纤无线电传输的背景下评估这种相干零差接收器 - 一种要求苛刻的应用设置，其中信号完整性的小幅下降会导致大的接收损失。我们对锁定方法进行连续模式表征，这使得零差检测成为可能，从而在相干接收过程中将电信号从光域透明地转换为电域。此外，正在研究以 1 MHz 帧速率和两个时分多路复用通道进行数据包级接收的锁定动态，这些通道由两个带有自由运行激光源的光发射器提供。对 64 进制正交调幅、正交频分复用无线电的光纤传输性能进行评估，数据包无线电信号之间的保护间隔为 2.7 μs。在发送器和接收器之间的光损耗预算大于 35 dB 的情况下，在 100 MHz 无线电带宽上获得 0.5 Gb/s 的数据速率，无需借助数字信号处理资源进行信号恢复。