Fluorescence Emission Centres and the Corresponding Infrared Fluorescence Saturation in a Bismuth-Doped Silica Fibre

We investigate the fluorescence characteristics of bismuth doped silica fibres with and without A1 co-dopant which are fabricated by means of modified chemical vapour deposition （MCVD） technique, and find that the fluorescences in the red region （centred around 750nm） and in the infrared region （centred around llOOnm） may originate from different emission sites in the fibre. Strong upconversion phenomena are observed in both Al-codoped and non A1 codoped bismuth fibres when the fibres are excited by an acoustic-optic Q-switched Nd：YVO4 laser. Both the aspects indicate that the upper energy level absorption reported in the work of the bismuth doped silica fibre lasers may result from the fluorescence emission sites that are not responsible for the infrared emission. It is thus expected that optimizing the compositions and the fabrication conditions of the fibre and then transferring more fluorescence emission centres are helpful for the infrared emission.     

基于双开口环结构的太赫兹超材料生物传感器

为了拓展超材料在太赫兹波段的生物传感应用,设计了一种双开口环结构的太赫兹超材料生物传感器,通过两个等效电容电感(LC)谐振实现了高折射率灵敏度传感。首先,使用有限积分技术(FIT)数值计算了该传感器的太赫兹光谱,并对其进行了结构尺寸优化。然后,在传感器表面放置了一层折射率可变的分析物,通过对不同透射光谱的计算分析,验证了该传感器具备161.06 GHz/RIU(RIU为折射率单位)的折射率灵敏度和1.98的品质因素(FOM)值。最后,采用传统光刻技术和剥离工艺在石英衬底上制作铜金属结构,制备了该传感器,利用其对牛血清白蛋白(BSA)溶液进行了实际测试,实验得到传感灵敏度为59.02 GHz/(ng·mm^-2)和检测下限为0.004 mg/mL。