碳点的性质及其在生物传感器领域的应用

碳点(carbon dots,CDs)作为一种具有优良生物相容性、低毒性和表面功能可调的新型碳基纳米材料,在生物传感领域具有极大的应用潜力.本文对碳点的生物效应、发光性质及其发光机理进行了简述,并根据传感机制的不同,将CDs在生物传感领域的应用分为荧光(fluorescence,FL)传感器、电致发光(electrochemiluminescence,ECL)传感器以及化学发光(chemiluminescence,CL)传感器三类进行综述.最后分析了CDs目前在生物传感器领域应用中存在的问题,并对其发展进行了展望.     

Temperature-calibrated fiber-optic refractometer based on acompact FBG-SMS structure

A novel all-fiber temperature-calibrated refractometer based on a compact fiber Bragg grating(FBG) single-multi-single(SMS)structure is proposed and experimentally demonstrated.The sensor head is composed of a FBG combined with a SMS structure,in which the middle multimode fiber(MMF)section is etched by a time-controlled hydrofluoric.The transmission dip of SMS is extremely sensitive to ambient refractive index(RI)variation,whereas the upstream FBG provides the necessary temperature information for RI calibration.All aforementioned functions are performed via a compact FBG-SMS structure not longer than 25 mm.The proposed sensing device provides a linear RI sensitivity over water or waterbased solutions(RI values near 1.33 at optical wavelengths for most biological and many environmental applications),and has temperature-calibration capability.Hence,the said refractometer is a good candidate for sensing in chemical and biological applications.     

基于改进的不动点迭代算法的低秩Gram矩阵的恢复

仿射限制条件下的低秩矩阵的恢复问题广泛地出现在控制、信号处理及系统识别等许多领域中.此问题可以凸松弛为带仿射限制条件的矩阵核范数的极小化问题.尽管后者能够转化为标准的半定规划问题求解,但是对于规模较大的矩阵其产生的计算量也很大.为此提出一种新的求解Gram矩阵核范数极小化问题的一阶算法-改进的不动点迭代算法(FPC-BB),并给出了算法的收敛性分析.算法以不动点迭代算法(FPC)中的算子分裂技术为基础,通过改进阈值算子Tv来求解低秩Gram矩阵的恢复问题.同时,还引入Barzilai-Borwein技术进行参数的选取,提高了算法的收敛速度.数值实验显示算法不仅能够很快地将低秩Gram矩阵精确地恢复出来,对于一些非低秩矩阵的恢复问题也能得出较好的结果.     

High-temperature sensor using a Fabry-Perot interferometer based on solid-core photonic crystal fiber

A micro Fabry-Perot interferometer(M-FPI) is constructed by splicing a short section of polarizationmaintaining photonic crystal fiber(PM-PCF) to an end-cleaved single-mode fiber with controllable offset. Due to the high effective optical path difference induced by the solid core of the PCF,the M-FPI has an ultrasmall cavity of approximately 110μm.The temperature sensitivity within a range from 33℃to approximately 600℃is measured to be 13.8 pm/℃,which shows good agreement with the theoretical result.This proposed sensor has the advantages of ultracompact size and high stability.Therefore,it is suitable for various space-limited sensing applications in harsh environments.     

基于激光火工系统的烟火泵浦激光技术

为研究烟火泵浦激光输出性能,对烟火泵浦激光器中泵浦源与激光晶体棒进行匹配实验研究和烟火泵浦激光器出光实验研究,以及烟火泵浦激光器光纤耦合输出实验研究。实验结果表明:烟火泵浦激光器选用锆氧闪光灯作为泵浦源,与工作物质为Nd∶YAG激光工作物质是相匹配的,烟火泵浦激光器输出能量4.82 J,满足烟火泵浦激光火工系统的能量输出需要;烟火泵浦激光器光纤耦合输出能量2.87 J,光纤耦合装置耦合效率达到50%以上,为烟火泵浦激光器用于战斗机舱盖抛放、飞行员座椅弹射逃生等火工系统研究提供了重要的技术支持。     

Temperature-independent refractive index measurement based on Fabry-Perot fiber tip sensor modulated by Fresnel reflection

A simple fiber tip sensor for refractive index(RI) measurement based on Fabry-Perot(FP) interference modulated by Fresnel reflection is proposed and demonstrated.The sensor head consists of an etchinginduced micro air gap near the tip of a single-mode fiber.The microgap and the fiber tip function as two reflectors to form a FP cavity.The external RI can be unambiguously measured by monitoring the fringe contrast of the interference pattern from the reflection spectrum.The experimental results show that the proposed sensor achieves temperature-independent RI measurement with good linear response.The proposed sensor achieves a high RI resolution of up to 3.4×10 5 and has advantages of low cost and easy fabrication.