用等效F—P方法研究微腔激光器DBR腔的特性

采用等效F－P腔方法对VCSEL中上、下两个DBR构成的微腔进行了研究,计算并讨论了不同周期数的DBR对微腔结构的反射率的影响。结果表明,激射波长两侧存在对称的反射率峰值。随着上下层DBR周期数的增加：峰值带逐渐变平、变宽;中心波长的凹隐逐渐变细、变窄;考虑吸收损耗,中心波长反向率逐渐增加。     

2-乙酰基雌酚酮和2-乙酰基雌二醇-17β-乙酸酯的晶体和分子结构

雌甾化合物的晶体结构已有较多的研究,本文用X射线衍射法对2-乙酰基雌酚酮(Ⅰ)和2-乙酰基雌二醇-17β-乙酸酯(Ⅱ)二化合物的晶体和分子结构进行了研究。 1 实验 1.1 晶体培养 样品(Ⅰ)和(Ⅱ)按文献所述方法合成。在室温下将(Ⅰ)的吡啶溶液置于充满甲醇蒸气的密闭容器中,使溶液保持过饱和状态而逐渐长成浅黄色的透明晶体。将(Ⅱ)溶于乙酸乙酯中,经重结晶得无色的透明晶体。     

Research on photodiode integrated with wide spectrum focusing reflector using nonperiodic subwavelength gratings

The fabrication and characterization of p-i-n photodiodes integrated with wide spectrum focusing reflectors using nonperiodic strip and concentric-circular subwavelength gratings are presented. The experimental results show that the gratings can reflect and focus the incident light on the absorber of the photodiode, and thus can simultaneously achieve high speed and high efficiency. For the gratings' integrated photodiodes, the responsivity is improved over a wide spectral range, and when the absorber was 600 nm and the mesa diameter was40 μm, a responsivity of 0.46 A/W at a wavelength of 1.55 μm and a 3 dB bandwidth of 21.6 GHz under a reverse bias of 3 V were simultaneously obtained.     

High-transmittivity non-periodic sub-wavelength high-contrast grating with large-angle beam-steering ability

We present a high-transmittivity non-periodic sub-wavelength high-contrast grating （HCG） with large-angle beam-steering ability for transmitted light. The phase front profile of transmitted light is a decisive factor to the beam-steering property of the HCG. By designing the structural parameters of the HCG, both beam steering and high transmittivity can be achieved. The properties of the beam steering and transmission are numerically studied with the finite element method. The results show that the transmittivity is up to 0.91 and the steering angle is 27.42° which is consistent with the theoretical 30°.     

Modeling of Fano Resonance in High-Contrast Resonant Grating Structures

A new model is presented for Fano resonance in resonant grating structure based on the temporal coupled mode theory. By using this model, the reflection spectrum can be reproduced with the information of eigenmode of the structure, which can be numerically calculated by the finite element method. Therefore, the eigenmode plays a key role in determining the profile of the line shape of the Fano resonance in the resonant grating structure. When the space of two grating modulations is decreased, the line shape experiences a significant change. Such a drastic change can be attributed to the increase of quality factor of the eigenmodes. Thus, our model not only provides a simple and intuitive understanding on the mechanism of Fano resonance, but it also offers a convenient way to engineer the line shape of the Fano resonance. The proposed model can be used in many applications, such as biosensors, optical filters, and optical switchers.     

理想光子探测器背景探测极限理论的误差分析

对于受背景噪声限制的理想光子探测器，利用普朗克分布函数进行推导，得到了较为精确的比探测率公式，并与传统的近似公式对比，进行了误差分析.结果表明：传统的近似公式误差量很小，一般情况下总是可用的.     

脉冲激光对类金刚石（DLC）薄膜的热冲击效应研究

强激光辐照红外热像系统时，可造成系统的干扰和破坏，激光的波长不同，对系统的破坏效果也不同.为了保护红外系统窗口以及提高窗口的透过率，红外窗口广泛沉淀类金刚石（DLC）薄膜.当入射的激光波长位于红外系统响应波段外时，激光对系统的破坏首先是激光对DLC薄膜的破坏.以波长为1.06μm的激光为例，研究了脉冲激光对DLC薄膜的损伤机理，建立了DLC薄膜的热冲击效应模型，并通过求解热传导和应力平衡方程，得出了薄膜的温度场和应力场分布.理论分析表明，热应力破坏在脉冲强激光对DLC膜的损伤机理中占主导地位.当 辐照能量密度为E₀=100mJ·cm^-2时，在薄膜表面距光斑中心约 40μm区域内的压应 力明显超出其断裂强度，将造成膜层的剥离、脱落.理论分析与实验结果基本相符，表明建 立热冲击效应模型的正确性. 关键词： 激光辐照 类金刚石（DLC）薄膜 热冲击效应     

可溶性碳纳米管光限幅特性的实验研究

利用实验的方法研究了可溶性碳纳米管对波长为1064和532nm激光的光限幅效应.分析了在 不同的样品浓度、不同的样品厚度情况下可溶性碳纳米管的光限幅特性，并对溶剂也进行了 光限幅实验.实验结果表明，在各种情况下可溶性碳纳米管对1064和532nm激光具有较强的 光限幅特性. 关键词： 可溶性碳纳米管 光限幅效应 强激光防护     

一维光子晶体的光学传输特性分析

采用等效F-P腔方法对一维光子晶体进行研究,计算并讨论不同周期数的一维光子晶体对光学传输特性的影响.计算结果表明,一维光子晶体具有光子禁带,表现为对光的高反射率;掺杂的一维光子晶体的光子禁带中央将出现频宽极窄的缺陷态,即光子局域,与复折射率和晶体周期数有密切的关系.所得结果与实验分析一致,证明了方法的有效性和实用性,并为光子晶体的设计提供依据.     

Defects in GaN Films Grown on Si（111） Substrates by Metal-Organic Chemical Vapour Deposition

We report the transmission-electron microscopy study of the defects in wurtzitic GaN films grown on Si(111) substrates with AlN buffer layers by the metal-organic chemical vapour deposition method. The In0.1 Ga0.9N/GaN multiple quantum well (MQW) reduced the dislocation density by obstructing the mixed and screw dislocations passing through the MQW. No evident reduction of the edge dislocations density by the MQW was observed. It was found that dislocations with screw component can be located at the boundaries of sub-grains slightly in-plane misoriented.