2μm单频激光输出掺铥硅锗酸盐玻璃光纤的研究

2μm single-frequency fiber laser has important applications in military and commercial fields due to its narrow linewidth, frequency-tunable, long coherent length and low noise, etc. This project plans to investigate a kind of Tm3+ doped silica-germanate glass fiber that can realize 2 μm single-frequency laser output with the aim of solving the fundamental scientific problems around compositional and structural design, luminescent mechanism and laser characteristics, etc. According to the modification and design of glass composition and structure, silica-germanate glass possessing low phonon energy, high Tm3+ solubility and high optical quality can be prepared. The effects of Tm3+ concentration, glass structure, absorption performance and pumping wavelength on 2μm luminescent properties in Tm3+ doped silica-germanate glass will be investigated to improve quantum efficiency and emission cross section. Inherent mechanism between glass compositions, fiber property, preform preparation and drawing process can be elucidated clearly. The microstructure of fiber cladding / core interface can be modified accurately to diminish loss and defects. The effect of linear cavity structure, thermo-optic effect, pumping and coupling methods, etc, on laser output parameters such as line width, noise and power will be investigated systematically. Finally, 2μm single-frequency laser output with ultra-narrow line width can be achieved from Tm3+ doped silica-germanate glass fiber.

2μm单频光纤激光具有线宽窄、频率可调、相干长度长、噪声低等独特性能，在军事与民用领域具有重要的应用价值。本项目拟研究一种可实现2μm单频激光输出的掺铥硅锗酸盐玻璃光纤材料，以解决2μm单频玻璃光纤材料的成分与结构设计、发光机理和激光特性等涉及的基础科学问题为目标。通过对玻璃成分和结构的设计与调控，实现低声子能量和高浓度掺杂的高光学质量硅锗酸盐玻璃制备；探明掺铥硅锗酸盐玻璃的2μm发光特性与离子浓度、玻璃结构、吸收性质和泵浦波长等的影响规律，提高其量子效率和发射截面。阐明玻璃组分-光纤性能-预制棒制备与拉制工艺之间的内在机理，对光纤包层/芯层界面微结构进行调控，消除缺陷和降低损耗。系统研究线形腔型结构、热光效应、泵浦与耦合方式等对光纤激光输出线宽、噪声、功率等参量的影响规律，最终在掺铥硅锗酸盐玻璃光纤中实现超窄线宽的2μm单频激光输出。

本项目研究了一种可实现2μm单频激光输出的掺铥硅锗酸盐玻璃光纤材料，以解决2μm单频玻璃光纤材料的成分与结构设计、发光机理和激光特性等涉及的基础科学问题为目标。.通过高温熔融法制备了硅锗酸盐玻璃和对比样品硅酸盐玻璃及锗酸盐玻璃。分析其物化性能和结构，发现硅锗酸盐玻璃具有较好热学性能、适中的声子能量和较高的稀土离子溶解度。.通过玻璃组分中Nd2O5和La2O3相对含量的调整，制备一系列的硅锗酸盐玻璃，研究其热学和光学特性。通过玻璃的吸收光谱和Judd-Ofelt理论分析，计算得到硅锗酸盐玻璃中Tm3+:3F4→3H6能级的自发辐射跃迁几率为301.67s-1和辐射寿命3.31ms。通过McCumber理论计算了受激发射截面，1.8μm发射截面为12.19×10-21 cm2。.研究了不同Tm2O3掺量的硅锗酸盐玻璃的光谱性质。Tm2O3最佳掺杂浓度值为1mol%。1.8μm处的受激发射截面为1.78×10-20cm2。.研究了Tm3+/Ho3+双掺硅锗酸盐玻璃，研究了玻璃热学性能和2μm光谱性能。Tm3+离子在硅锗酸盐玻璃中可有效地敏化Ho3+，其能量转移效率可达52%。.研究了Tm3+/Yb3+双掺硅锗酸盐玻璃，通过Yb3+离子敏化Tm3+离子，得到发光中心在1.8μm的荧光。当Tm2O3和Yb2O3浓度分别为0.5mol%和1mol%时，1.8μm荧光强度最强。.制备了大尺寸掺铥硅锗酸盐玻璃及光纤，最终在掺铥硅锗酸盐玻璃光纤中实现超窄线宽400mW的2μm单频激光输出。