A low-threshold multiwavelength Brillouin fiber laser with double-frequency spacing based on a small-core fiber

We demonstrate multiwavelength Brillouin fiber lasers (MWBFLs) with double-frequency spacing based on a small-core fiber (SCF) and a standard single-mode fiber (SMF), which have core diameters of 5 and 8.8 μm, respectively. Experimental results show that the SCF-based MWBFL exhibits a higher laser output power and a lower pump threshold. The output powers of the SCF-based MWBFL are > 1.4 times those of the SMF-based MWBFL. Moreover, the threshold power required to generate each channel of the SCF-based MWBFL is 59% that of the SMF-based MWBFL. When the same pump power of 180 mW is injected, the number of laser channels generated for the SCF-based MWBFL is 13, which is twice that generated for the SMF-based MWBFL. In addition, the SCF-based MWBFL exhibits good wavelength tunability from 1535 to 1565 nm and temporal stability over an hour.     

中红外色散平坦渐减光纤设计

设计了一种以As2S3玻璃为纤芯、碲酸盐玻璃为微结构包层的锥形光子晶体光纤.该结构光纤兼具阶跃折射率光纤和光子晶体光纤双重特性,具有色散调制灵活性高且限制损耗低等优点.模拟结果表明:优化该光纤结构包层空气孔径、孔间距、纤芯直径等特征参量,使参量之间及参量与椎区长度之间满足特定线性关系时,该光纤在2~4.5μm中红外波段呈现色散平坦渐减特性;对该光纤微包层进行折射率~1.6的液体油填充处理,色散曲线对称性及平坦性得到进一步优化.该光纤在超短脉冲压缩与展宽、色散波、光孤子及中红外平坦超连续谱产生等领域应用潜力巨大.     

中红外色散平坦硫系光子晶体光纤设计及性能研究

本文以自制Ge20Sb15Se65硫系玻璃为基质材料,设计一种正八边形结构色散平坦型中红外硫系光子晶体光纤,并采用多极法对其中红外色散和传输特性进行数值研究.结果表明:控制该光纤占空比(d/Λ)在0.323—0.367之间,其色散及传输特性在3—5μm范围内可调.当孔间距Λ=3.4μm,孔直径d=1.1μm时,光纤在4.1—4.9μm波段的色散值在0.8—0.8 ps·nm 1·km 1波动,且具备单模低损耗传输(Loss0.049dB/m),小模场面积(Aeff8.46μm2)特性,适合于中红外非线性应用领域.     

4.3μm低损耗硫系空芯光子带隙光纤结构设计及性能研究

运用平面波展开法分析As2S3、Ge20Se65Sb15和As2Se3硫系玻璃光纤在不同空气填充率下的带隙分布图,分析结果表明三种材料在空气填充率提高到0.75时,光子带隙与空气线均出现交汇模式,且带隙宽度大,纤芯空气孔中适宜进行激光传输.运用有限元法分析不同纤芯孔直径的Ge20Se65Sb15硫系玻璃空芯光子带隙光纤的基模限制损耗和有效模场面积,结果表明纤芯直径9.2μm时限制损耗最低,模场面积较小.通过优化光纤的结构参量,适合于4.3μm波长处高功率中红外激光传输的空芯光子带隙光纤,其限制损耗为0.00472dB/m,有效模场面积为58.046μm2.