波长可调谐硫化铅量子点掺杂石英放大光纤研究

Doped amplification fibers can be used to build optical communication systems, such as fiber amplifiers, lasers, broadband light sources, optical fiber sensor. However, with the rapid development of optical communication, the existing amplification fiber has been unable to meet its needs in terms of bandwidth, gain and other performances. Based on the atomic layer deposition (ALD) technology, lead sulfide (PbS) quantum dots with size and spatial distribution as the doping source, in combination with the secondary heat treatment optimization method, the aim of the project to develop the quantum dots doped silica fibers with high fluorescent efficiency and wavelength tunable. The research contents include: the establishment of theoretical model of optical irradiation characteristics for PbS quantum dots doped silica optical fiber; exploring the key technologies of optical fiber preparation based on ALD and modified chemical vapor deposition (MCVD); based on improved drawing technology, research formation mechanism of PbS quantum dot with different particle size distribution, and its effect on improving the luminous efficiency, gain bandwidth and center wavelength; by optimizing heat treatment technology further realization the size and spatial distribution of quantum dots in the fiber core. The key points of the proposed project are to solve the problems of gain bandwidth narrow, central wavelength fixation and lower luminous efficiency in existing amplifying fiber. The research results can be used to develop new type of optical fiber communication devices.

掺杂放大光纤可用于构建光纤放大器、激光器、宽带光源及光纤传感器等光通信系统。然而，随着光通信的迅猛发展，现有放大光纤在带宽、增益等性能方面已无法满足其需求。本项目提出基于原子层沉积（ALD）技术，以尺寸、空间分布可调控的硫化铅（PbS）量子点作为掺杂源，结合二次热处理优化方法，旨在研制高荧光效率、近红外波长可调谐的掺杂石英光纤。研究内容包括：建立量子点掺杂石英光纤光辐射特性理论模型；探索基于ALD和改进的化学气相沉积法（MCVD）的光纤预制棒制备关键技术；研究基于改进的拉丝工艺，不同粒径分布的PbS量子点形成机理，及其对提高发光效率、增益带宽及中心波长等所起的作用；采用热处理优化技术进一步实现纤芯中量子点的尺寸分布和空间分布调控。本项目重点拟解决现有放大光纤中增益带宽窄、波长固定、发光效率低等关键问题，研究成果可用于研制新型的光纤通信器件。

随着5G/6G，大数据、人工智能、互联网+等技术的飞速发展，数据量激增。而单模光纤传输容量增长乏力，已无法满足数据量激增的需求。如何提高单模光纤传输容量，是目前急需解决的问题，而宽带光纤放大器是关键核心问题之一。本项目以PbS量子点作为增益介质，研制一种量子点掺杂石英光纤并应用光纤放大器系统。理论方面，基于密度泛函理论（DFT）建立了PbS掺杂石英光纤材料微观结构模型，并对其结构特性和光学特性进行了仿真；基于有限差分波束传输法（FD-BPM）建立了PbS量子点掺杂光纤放大器的理论模型。将量子点的光辐射特性和光纤的光传输动态相结合，建立放大自发辐射光沿光纤传输的功率动态方程。研究了光纤结构特性、量子点特性及测试系统参数选择等对放大器增益及噪声特性的影响。实验方面，基于原子层沉积（ALD）技术制备了高质量的PbS纳米材料，获得尺寸为5-10 nm的PbS QDs，通过热处理，在1000~1600 nm范围内的波长可调谐发光；基于改进的化学气相沉积（MCVD）与ALD技术相结合技术制备了PbS量子点掺杂石英光纤。在1050-1350 nm内获得6.04-9.23 dB的净增益，3 dB带宽约300 nm，超宽带增益特性是由于纤芯中多尺寸PbS量子点的作用。进一步探索性开展PbS量子点与Er共掺石英光纤，在1525-1575 nm波段范围产生的开关增益值为最大为25.8 dB，净增益值为24.7 dB。说明共掺可以有效的提高带宽和增益强度。同时，通过热处理技术，实现了对纤芯中PbS量子点尺寸的调控。量子点掺杂光纤在波长调谐、宽带、高增益、低损耗、低噪声等方面具有明显优势，在光纤通信领域具有巨大的应用潜力。