Improved silica fiber with enhanced ultraviolet transmission

When a silica optical fiber is used for transmitting ultraviolet (UV) light, the problems associated with the damage and transmission deterioration of silica fiber in the UV region need to be solved in the fabrication process. In this paper, an improved silica fiber fabrication process was presented to enhance UV transmission, which combined the UV pre-irradiation on high-OH concentration preform with heat treatment while drawing fiber. The impact of the structural defects and color centers was diminished greatly by the new method of fabrication. The experimental results accorded with the theoretical analysis, and transmission was improved about 0.4-0.7 dB/m for wavelength from 350 to 400 nm.     

Characteristics of an add-drop filter composed of a Mach-Zehnder interferometer and double ring resonators

A planar lightwave circuit (PLC) add-drop filter is proposed and analyzed, which consists of a symmetric Mach-Zehnder interferometer (MZI) combined with double microring resonators. A critical coupling condition is derived for a better box-like drop spectrum. Comparisons of its characteristics with other schemes, such as a MZI with a single ring resonator, are presented, and some of the issues about device design and fabrication are also discussed.     

跑道形玻璃波导谐振腔滤波器的研制

采用Ag+-Na+离子工艺，在K9玻璃上制备了跑道形波导谐振腔滤波器.测试得到该滤波器自由光谱范围为FSR=0.177 nm，对比对为Cr＝7.5 dB.同时分析得到耦合器的耦合系数为κ=0.916，耦合器和环形腔的损耗因子分别为δ=0.55,γ=0.48.耦合器的两波导几乎相连、条波导边缘不规则和一次离子交换波导表面缺陷是造成该波导滤波器具有较大损耗的主要原因.通过改进工艺技术降低波导损耗，该滤波器可以用于光通信、传感等领域，也可与其它波导结构相结合实现新的功能.