Author Affiliations
Abstract
1 Peng Cheng Laboratory, Shenzhen, China
2 Shanghai Jiao Tong University, State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai, China
3 University of L’Aquila, Department of Physical and Chemical Sciences, L’Aquila, Italy
We propose a joint look-up-table (LUT)-based nonlinear predistortion and digital resolution enhancement scheme to achieve high-speed and low-cost optical interconnects using low-resolution digital-to-analog converters (DACs). The LUT-based predistortion is employed to mitigate the pattern-dependent effect (PDE) of a semiconductor optical amplifier (SOA), while the digital resolution enhancer (DRE) is utilized to shape the quantization noise, lowering the requirement for the resolution of DAC. We experimentally demonstrate O-band intensity modulation and direct detection (IM/DD) transmission of 124-GBd 4 / 6-level pulse-amplitude modulation ( PAM ) -4 / 6 and 112-GBd PAM-8 signals over a 2-km standard single-mode fiber (SSMF) with 3 / 3.5 / 4-bit DACs. In the case of 40-km SSMF transmission with an SOA-based preamplifier, 124-GBd on-off-keying (OOK)/PAM-3/PAM-4 signals are successfully transmitted with 1.5 / 2 / 3-bit DACs. To the best of our knowledge, we have achieved the highest net data rates of 235.3-Gb / s PAM-4, 289.7-Gb / s PAM-6, and 294.7 Gb / s PAM-8 signals over 2-km SSMF, as well as 117.6-Gb / s OOK, 173.8-Gb / s PAM-3, and -231.8 Gb / s PAM-4 signals over 40-km SSMF, employing low-resolution DACs. The experimental results reveal that the joint LUT-based predistortion and DRE effectively mitigate the PDE and improve the signal-to-quantization noise ratio by shaping the noise. The proposed scheme can provide a powerful solution for low-cost IM/DD optical interconnects beyond 200 Gb / s.
look-up-table digital resolution enhancer quantization noise semiconductor optical amplifier pattern-dependent effect pulse-amplitude modulation Advanced Photonics Nexus
2024, 3(3): 036007
1 中国科学院自适应光学重点实验室, 四川 成都 610209
2 中国科学院光电技术研究所, 四川 成都 610209
3 中国科学院大学, 北京 100049
4 宜宾学院物理与电子工程学院, 四川 宜宾 644007
追踪了由远场光电探测器采样宽度限制引入的量化噪声在算法实现过程中的传递,分析了其对算法在波前像差校正中的效果和收敛速度产生影响的原因。根据斯特列尔比值(SR)的变化,提出了一种基于动态区域提取的模式复原算法,并利用18阶和33阶Zernike多项式模拟得到的符合Kolmogrove大气湍流功率谱的波前对该算法进行数值计算。计算结果表明:采用动态区域提取的复原算法校正波前像差,在12位相机采样宽度和33阶初始像差情况下,算法经31次迭代后收敛,波前复原残差均方根为0.058λ(λ为波长),SR达0.9以上。该算法减小了量化噪声的影响,无波前传感自适应光学系统的收敛速度和校正效果得到显著提高。
大气光学 自适应光学 量化噪声 动态区域提取 模式复原 激光与光电子学进展
2017, 54(11): 110101