Novel sol–gel synthesis of transparent and electrically bistable LiNbO<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> nanocomposites thin films

The morphological and electrical characterization of transparent nanostructured LiNbO₃–SiO₂ thin films synthesized by a novel sol–gel route is reported. Films annealed at different temperatures exhibit different size of the nanocrystals, as demonstrated by Atomic Force Microscopy and Glancing Incidence X-ray diffraction. The dc electrical measurements performed on planar devices reveal electrical bistability. A clear relationship between the electrical bistability and the size of LiNbO₃ nanocrystals embedded in the matrix is observed.     

ESI-FTICRMS与更换底物保护基团方法联用表征烯醇反应中间体

更换底物保护基团的化学方法与质谱、同位素标记以及核磁方法联用表征钯催化的烯醇环化反应中间体。实验表明更换底物的保护基团方法可以明显降低反应速度,延长关键中间体离子的存活寿命,不仅清晰地观察了反应的整个进程而且成功地捕获检测表征了其中关键中间体离子。进一步,串联质谱(SORI-CAD)方法研究了其中一些中间体离子的气相裂解反应行为,归纳总结其气相裂解反应的途径。结合同位素标记的结构为它们结构的确证提供了丰富信息。     

Noticeable positive Doppler effect on optical bistability in an N-type active Raman gain atomic system

We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity.It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region,which has been known as the positive Doppler effect on optical bistability.In addition,we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.     

Controllable optical bistability of Bose-Einstein condensate in an optical cavity with a Kerr medium

We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with a Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value.     

Optical bistability using quantum coherence in a microwave-driven four-level atomic system

The behavior of the optical bistability (OB) is investigated in an optical system which consists of a four-level atomic system with a microwave drive field and an optical cavity. It is found that the optical bistability can be accomplished by adjusting different physical parameters in both steady and transient process. Due to the existence of the microwave drive field, the optical bistability can be also obtained even under weak coherent coupling field condition. Since the intensity and phase of microwave drive field can be conveniently modulated, this optical system provides a new experimental method to test the optical bistability theory.     

FP腔中光驱动微悬臂的双稳效应的研究

研究了高灵敏度悬臂梁与光纤端面构筑的低精细度FP型光腔中光驱动的悬臂梁振动的双稳效应。通过改变输入到光腔内的激光功率,检测与之相应的悬臂梁的形变。在实验中发现悬臂梁的形变随激光功率的改变呈现非线性变化的关系,在激光功率增大到一定闽值时可以诱导产生光力双稳效应。通过改变光腔初始腔长成功实现了对产生光力双稳效应阈值的调节。     

弱光反馈下正交时变光注入VCSEL的双稳特性研究

基于垂直腔面发射激光器(VCSEL)的自旋反转模型(SFM),研究了弱光反馈下正交时变光注入VCSEL的双稳特性。研究结果表明,当副激光器(S-VCSEL)受到主激光器(M-VCSEL)正交时变光注入时,弱光反馈的引入不改变正交时变光注入VCSEL的双稳宽度随光注入扫描速率增大而增大的性质;对于确定的光注入扫描速率,随着反馈强度的增大,双稳宽度将变窄;当M-VCSEL与S-VCSEL之间存在频率失谐Δν(等于νm-νs,νm、νs分别为主、副激光器自由运行时的频率)时,随着Δν从负值逐渐增加到正值,双稳宽度总体呈现先减小后增大的趋势,无反馈时在负频区域双稳环宽度呈现的较大波动在引入光反馈后可得到一定程度的抑制。     

Two optical bistability domains in composites of metal nanoparticles with nonlinear dielectric core

It is shown that the local field in metal spherical particles with a dielectric core in an external varying electric field has two maxima at two different frequencies. The second maximum becomes more important with an increment in the metal fraction. Due to the nonlinear dielectric function of the core, the composite of these inclusions may have two optically induced bistability domains at different frequencies. At rather high metal fraction, two bistability domains merge and form one entire bistability domain. The parameters of these domains are studied numerically. The paper focuses on the second bistability domain, which has not been discussed in the literature so far. This domain exists in a comparatively narrow frequency range and its onset fields are lower than those of the first bistability domain. The lowest bistability onset fields are obtained in the entire domain. This peculiarity of the optical induced bistability in the metal composite with small dielectric cores can be attractive for possible applications.     

Oscillator models for multiphoton optical bistability and phase conjugacy

Nonlinear oscillator models are constructed to treat the bistability in situations involving elementary excitations in solids. Such models are shown to be useful not only in describing single photon but also multiphoton bistability. The resulting bistability both with and without cavity is considered. The two-photon excitonic bistability in CuCl is in detail. The effect of local field corrections can also be incorporated, in a simple manner, in such models.     

ZnSe-CdZnse多量子阱光双稳器件的研制

本文采用电化学选择性腐蚀工艺对GaAs衬底蚀孔,在其上获得了大面积具有光滑表面的Ⅱ-Ⅵ族半导体多量子阱外延膜.通过在其表面蒸镀反射膜,制成了高质量的F-P腔,制备出ZnSe-CdZnSe多量子阱F-P腔光双稳器件.