I~-的光电化学氧化与光助充电二次锂离子电池

采用扫描电子显微镜、X射线衍射和粉末微电极分别考察了TiO2粉末的形貌、结构以及氧化I-的光电化学行为.结果表明,TiO2粉末晶型为锐钛矿,粒径在100～200 nm范围内.在光照条件下,在TiO2半导体电极上电化学氧化I-生成I2的超电势数值降低约1 V.以TiO2/ITO和Li4Ti5O12分别作为正负极,电解液为碳酸丙烯酯(PC)+LiClO4+LiI,并以聚偏氟乙烯(PVDF)作为隔膜构成分隔式电解池,进行整体电解并结合紫外-可见光谱进行分析.结果表明,该装置在光照条件下电池充电电压比非光照条件下的充电电压降低约0.9 V,且充电效率接近100%.该光电化学装置是一种可以利用光能充电的二次锂离子电池.     

Reversed pyramids as novel optical micro-cavities

Pyramidal micro-cavities represent a novel promising class of semiconductor optical cavities. In contrast to our previous approach based on pyramids sitting on distributed Bragg reflectors, we investigate reversed freestanding GaAs pyramids. The latter are achievable by a wet-chemical etching process where an AlAs sacrificial layer in the epitaxially grown layer structure is used. In freestanding GaAs pyramids, light is simply confined by total internal reflection at the interface of the high refractive index material GaAs to the surrounding. Due to strong optical confinement within the pyramidal shape, small mode volumes are expected. Quality factors up to 3000 were measured in first structures. However, simulations suggest the possibility of much higher values. Therefore, these freestanding pyramids are promising for an optimized ratio between quality factor and mode volume, which is crucial for quantum-optical applications.     

AlxGa1-xAs/AlyGa1-yAs微腔中的激子吸收增强效应

文章采用Al_xGa_1-xAs/Al_yGa_1-yAs微腔结构,研究了微腔中激子的吸收行为,在室温下观察到了激子吸收的增强效应,激子的峰值吸收强度是自由空间中激子吸收强度的2,6倍;我们从激子与光波场相互作用和腔中模函数的分布建立了计算.激子先吸收的模型,文中给出的微腔结构的数值计算表明激子的吸收增强与实验结果相一致;数值计算表明,微腔中激子吸收的强弱不仅与上、下两腔镜的反射率和腔长有关,而且还取决于量子阱在腔中的位置.     

A photonic crystal biosensor with temperature dependency investigation of micro-cavity resonator

A two dimensional photonic crystal biosensor implemented by waveguides and microcavity is theoretically investigated. The designed structure has high quality factor about 15,000 and sensitivity approximately 141.67 nm/RIU, which are important parameters in biosensing applications. Also there is a linear dependency between resonant wavelength shift and refractive index changes. Since water is the main component of human organism, the temperature and wavelength dependence of proposed microcavity is investigated. The results show that the structure has good temperature stability. The temperature sensitivity is about −0.0142 nm/°C.     

语音信号调制的微腔半导体激光器的抗噪音性能

假定微腔半导体激光器输入调制信号为实际语音信号,伴随语音信号的噪音为加性白噪音,在小信号近似下,得到了电流调制和自发发射寿命调制下激光器的传递函数;在大信噪比的前提下,对激光器进行了频域分析,得到了不同参量下的信噪比增益.数值模拟结果表明,在偏置电流的变化范围内,存在极低信噪比增益区,大自发发射因子、小自发发射寿命有利于使该区变窄;语音信号的通带范围和功率谱密度分布特征参量的适当选取,可以使激光器的抗噪音性能在偏置电流的某段范围内得以提高.     

Transient Optical Characteristics of Broad Absorption Band Excitons Modulated by Micro-cavity

The understanding of light-matter interaction within micro-cavity lays the basic groundwork for many future photon-related technologies and applications. We prepared low quality metal-insulator-metal(MIM) micro-cavity consisting massive two-level broad absorption band dye(Nile Red) excitons, which randomly dispersed in SU-8 polymer negative resist matrix and measured their optical characteristics. New binate transmission peaks with large energy separation(so-called Rabi-splitting phenomenon) and their angular anti-crossing behavior in consequence of the interaction between dye excitons and confined photons were observed. It was also confirmed that the separated energy can be tuned by changing the doped exciton concentrations. Time-resolved transient absorption measurements showed that such an interaction is indeed a coherent one but rather a strong coupling one and one can modulate such a coherent mechanism by easily adjusting the detuning between dye excitons and confined cavity photons. This work may provide a comprehensive and deep understanding for such massive broad absoprtion band excitons-doped MIM micro-cavities and represent a further step to realize optical cavity-modulated devices in future.     

一维光子晶体微谐振腔的调谐特性与品质因子

利用传输矩阵法研究了对称结构和非对称结构一维光子晶体微谐振腔的调谐特性和品质因子.研究发现：当缺陷层光学厚度增加时,缺陷模中心波长也会随着增加即向长波方向移动,微谐振腔的调谐特性与缺陷层两边介质的折射率有关;相比于对称结构,非对称结构能在较小的缺陷层光学厚度变化范围内实现较大波长范围的线性调谐;品质因子随缺陷层厚度的增加先增大后减小,在缺陷模中心波长为λ0时可达最大值;高低折射率介质层的排布对微谐振腔品质因子有影响.     

圆对称光栅对微腔激光器中光波的控制

本文通过幂级数法和逐差法对不同形式圆对称光栅微腔结构中的光场分布进行模拟,验证各自的适应范围及正确性。模拟表明光栅可以改变微腔中的光波,合理地选择轴心高折射率区的半径及外围光栅的形状和参数,可以增加模式间隔和有源区内基模光波能量的比例,从而提高选模性能。     

Multichannel W3 Y-branch filter in a two dimensional triangular-lattice photonic crystal slab

We demonstrate the design, fabrication and characterization of a highly efficient multichannel W3 Y-branch filter in a two dimensional triangular-lattice photonic crystal slab. The coupling properties between high-order waveguide modes and fundamental resonant modes are investigated. By finely adjusting the size of resonant cavities, four higher-order mode channels with different output wavelengths are experimentally realized, which is in agreement with the theoretical simulations. The results show that this kind of filter may be useful in optical integrated circuits with high coupling and transmission efficiency.