基于光时分复用与偏振调制的高性能光数模转换技术研究

High-resolution and high-speed digital-to-analog converter (DAC) is highly demanded in modern communication, radar and measurement systems. Photonic DAC can break through the electronic bottleneck, and it is an inevitable trend for future high performance DAC. However, the current photonic DAC usually has a low resolution and limited sampling rate. To solve the above problems, a high-resolution and high-speed photonic DAC based on optical time division multiplexing and polarization modulation is proposed and investigated in this project. The main properties and innovations of this project are as follows. Firstly, by generating and using weighted multi-wavelength optical pulses with high extinction ratio, stable amplitude and low time jitter, the noise can be suppressed in the optical signal source, which leads to a high resolution of the photonic DAC. Secondly, a bipolar-DAC is achieved based on polarization modulation and balanced photo detection. This scheme can increase the signal-to-noise ratio and thus leads to a high-resolution and a large dynamic range. Thirdly, the sampling rate of the photonic DAC can be increased by optical time division multiplexing technique, which can break through the speed limitation caused by the electric-optical modulator. The research will be carried out through both theoretical and experimental investigations. The results of the project are expected to realize the leap frog development of high-resolution and high-speed photonic DAC. In addition, the proposed photonic DAC can powerfully provide technical supports for applications such as arbitrary waveform generation in communication, radar and measurement systems.

现代通信、雷达与测试系统对高精度与高速率的数字模拟转换器（DAC）具有十分迫切的需求。基于光子技术的DAC（光DAC）能突破电子瓶颈限制，是未来高性能DAC的必然发展方向。然而，目前的光DAC面临精度低、采样速率受限的问题。针对以上问题，本项目拟提出并研究基于光时分复用与偏振调制实现的高精度、高采样速率的光数字模拟转换技术。项目的特色与创新之处为：①通过产生并利用消光比高、幅度稳定、时间抖动低的不同权重的多波长光脉冲，从光信号源头降低噪声，提高DAC的精度；②基于偏振调制与平衡光电探测实现双极性输出的光DAC，能提升DAC的精度与动态范围；③利用光时分复用技术提高光DAC的采样速率，能突破电光调制器对光DAC采样速率的限制。本项目通过理论与实验两方面对所提光DAC进行研究，研究成果有望推进光DAC向高速率与高精度的跨越式发展，为通信、雷达与测试系统中的任意波形发生等应用提供有力的技术支持。

随着通信与雷达等系统向高频、宽带方向发展，目前的电子数模转换与波形产生系统已经越来越难以应对高性能电子系统的需求。本项目针对通信、雷达等系统对高速数字模拟转换器与波形产生技术的迫切需求，开展了基于光子技术的光数模转换与波形产生及其应用的研究工作。在国际上首次提出并研究了一种新型的串行光数模转换系统，实验实现了10GSa/s的4-bit光数模转换系统,其有效比特数达到3.49bit。在此基础上提出利用偏振复用技术简化光数模转换系统复杂度的方法，实验研究结果证明此方法能讲系统复杂度降低为原来一半。针对所提出的光数模转换系统对光脉冲或光频梳的需求，本项目还提出并研究了基于偏振调制与光纤色散产生高速光脉冲等方案，均取得了优良的性能。在利用光子波形产生技术方面，本项目提出并研究了基于先进电光调制技术、半导体注入激光器技术以及光电振荡器的微波波形产生方法，能产生通信与雷达系统需要的超低相位噪声微波信号、相位编码信号、线性调频信号等各种波形。在以上研究基础上，开展了基于光数模转换与波形产生技术在雷达系统中的应用研究，提出了一种先进的超宽带微波光子雷达架构，实现雷达成像的分辨率高达2厘x2厘米。本项目的研究成果有望推进光数模转换与波形产生技术向高速率与高精度的跨越式发展，为通信、雷达与测试系统中的任意波形发生等应用提供有力的技术支持。.本项目严格按照预期计划与经费预算执行，圆满完成了项目预期指标。在本项目的资助下共发表期刊论文26篇（SCI论文25篇），会议论文23篇（国际会议特邀报告5篇），申请发明专利10项（5项已授权）。培养博士生3名，硕士生4名。