面向模分复用通信的少模光波导放大器

The mode division multiplexing(MDM) technology based on few-mode optical fiber transmission system has overcome the capacity limit of single-mode communication system and has received extensive attention. However, the loss of signal mode generated in the MDM system seriously affects the performance of the MDM system, which needs to be compensated by optical amplifiers. The traditional optical amplifiers can only amplify a single mode, which cannot meet the requirement of MDM system. Therefore, there is an urgent need for few-mode optical amplifiers that can amplify multiple-signal mode groups simultaneously to solve this problem. Erbium-doped few-mode optical waveguide amplifier can effectively compensate the mode coupling loss and transmission loss generated in the on-chip and short-distance mode division multiplexing systems. In this proposal, the applicant combines the advantages of erbium-doped organic polymer with high doping concentration, low cost and easy processing to study the few-mode optical waveguide amplifier for mode division multiplexing system, which can amplify multiple-signal mode groups proportionally with high gain. By studying the luminescence enhancement mechanism and the improved doping method, the active organic polymer material with high quantum efficiency and high earth ions doping concentration will be synthesized. By analyzing the principle of multi-signal mode amplification, the structure and size of few-mode waveguide will be optimized, multi-signal mode transmission and effective amplification will be realized in a single waveguide. For the sake of equalization of the modal gain, the scheme of reconfigurable pump mode will be explored and the erbium doped distribution will be optimized. The few-mode waveguide amplifier with a net average gain of more than 5dB and a differential modal gain lower than 1dB will be developed.

基于少模光纤传输模分复用（MDM）技术，可以突破单模光纤通信系统的容量极限，受到广泛关注。然而MDM系统中产生的模式信号的损耗严重影响了MDM系统的性能，需要光放大器对其进行补偿。传统的光放大器只能对单一模式信号进行放大，无法满足MDM系统的需求，迫切需要同时放大多个信号模式的少模光放大器来解决这一问题。铒掺杂少模光波导放大器能够有效补偿片上及短距离MDM系统中产生的损耗，改善MDM系统的性能，研究意义重大。本项目结合铒镱共掺有机聚合物掺杂浓度高、成本低、工艺简单等优势，研究面向MDM系统的高增益补偿、均衡放大的少模光波导放大器。拟研究铒镱离子发光增强机制和掺杂方式，合成高量子效率和高掺杂浓度的有机光放大材料；分析多信号模式放大原理，优化设计少模波导结构及尺寸，实现多信号模式有效放大；探索泵浦结构和铒离子分布调控方案，实现增益均衡；研制出平均模式净增益大于5dB，模式间增益差小于1dB。

基于少模光纤传输模分复用技术将模式作为复用传输信道，能够突破单模光纤通信系统的容量极限，受到了广泛关注。但在系统中，由大量核心模式器件，如模式转换器、模式复用/解复用器、调制器等产生的模式信号的损耗严重影响了模分复用系统的性能，阻碍了模分复用通信发展，需要光放大器对其进行补偿。然而传统的光波导放大器仅能对单一模式信号进行放大，无法满足模分复用系统的需求，迫切需要多个信号模式同时放大的少模光放大器来解决这一问题。针对这一需求，我们结合铒镱共掺有机聚合物掺杂浓度高、成本低、工艺简单等优势，研究面向模分复用系统的高增益补偿、均衡放大的少模光波导放大器。本项目主要研究了高质量有机光放大材料的合成与分析、聚合物少模光波导放大器的数值模拟与优化设计、泵浦结构调控增益方案的整体设计、高质量有机少模波导的制备及少模光波导放大器的测试等方面内容。研制出了粒径均一的异质壳层包覆的核-壳结构的纳米粒子，纳米粒子包覆壳层后的荧光发射强度较未包覆壳层的纳米粒子提升了近6倍。合成了一系列高稀土离子掺杂的有机聚合物材料：物理掺杂有机光放大材料Er3+的掺杂浓度较已报道的铒离子在聚合物中的掺杂浓度提高1.2倍；基于化学键键合的共聚材料，Er3+的掺杂浓度较目前已报道的铒离子在聚合物中的掺杂浓度提高了一个数量级，同时材料的稳定性也得到了极大的改善。研制出了面向模分复用的三模光波导放大器，采用980 nm LP01和LP21b双模式泵浦，当LP01模式泵浦功率为320 mW，LP21b模式泵浦功率为120 mW时，1555 nm波长的三模式信号光被同时放大，获得平均模式增益10.4 dB，模式间增益差仅为0.4 dB，实现了模式增益均衡，噪声指数小于4.5 dB。器件在整个C波段内仍可实现有效放大，平均模式增益超过7.4 dB。少模光波导放大器的研制成功，将推动模分复用技术在片上及短距离通信系统中的大规模使用，对模分复用系统的科研和产业化发展起到积极的促进作用，意义重大。