Hugues-Salas E, Giddings R P, Jin X Q, Hong Y, Quinlan T, Walker S, Tang J M
School of Electronic Engineering, Bangor University, Dean Street, Bangor, LL57 1UT, UK.
Opt Express. 2012 Sep 10;20(19):21089-100. doi: 10.1364/OE.20.021089.
Reflective electro-absorption modulation-intensity modulators (REAM-IMs) are utilized, for the first time, to experimentally demonstrate colorless ONUs in single-fiber-based, bidirectional, intensity-modulation and direct-detection (IMDD), optical OFDM PONs (OOFDM-PONs) incorporating 25 km SSMFs and OLT-side-seeded CW optical signals. The colorlessness of the REAM-IMs is characterized, based on which optimum REAM-IM operating conditions are identified. In the aforementioned PON architecture, 10Gb/s colorless upstream transmissions of end-to-end real-time OOFDM signals are successfully achieved for various wavelengths within the entire C-band. Over such a wavelength window, corresponding minimum received optical powers at the FEC limit vary in a range as small as <0.5 dB. In addition, experimental measurements also indicate that Rayleigh backscattering imposes a 2.8 dB optical power penalty on the 10 Gb/s over 25 km upstream OOFDM signal transmission. Furthermore, making use of on-line adaptive bit and power loading, a linear trade-off between aggregated signal line rate and optical power budget is observed, which shows that, for the present PON system, a 10% reduction in signal line rate can improve the optical power budget by 2.6 dB.
反射型电吸收调制强度调制器（REAM-IM）首次被用于在基于单光纤的双向强度调制和直接检测（IMDD）光正交频分复用无源光网络（OOFDM-PON）中进行无色光网络单元（ONU）的实验演示，该网络采用了25千米的标准单模光纤（SSMF）和光线路终端（OLT）侧注入的连续波光信号。对REAM-IM的无色特性进行了表征，并据此确定了最佳的REAM-IM工作条件。在上述无源光网络架构中，成功实现了整个C波段内各种波长的10Gb/s无色上行端到端实时OOFDM信号传输。在这样一个波长窗口内，前向纠错（FEC）极限下相应的最小接收光功率变化范围小至<0.5dB。此外，实验测量还表明，瑞利背散射在25千米上行OOFDM信号传输中对10Gb/s信号造成了2.8dB的光功率代价。此外，利用在线自适应比特和功率加载，观察到聚合信号线速率和光功率预算之间存在线性权衡，这表明，对于当前的无源光网络系统，信号线速率降低10%可使光功率预算提高2.6dB。
