Plane Waves Propagating in Chiral Plasma and Chiral Ferrite Media

Plane wave propagation in chiral plasma and chiral ferrite media is studied in kDB coordinate system. General wave equations and characteristic equations of plane waves propagating along an arbitrary direction in chiral plasma and in chiral ferrites are derived in simple formulations respectively. Four wavenumbers and their corresponding dispersion characteristics are resulted for propagation both along and normal to the biasing magnetic field. When plane wave with negative helicity propagates along the biasing magnetic field in chiral ferrites, backward waves emerge. However backward waves occur with both positive and negative helicities when propagating along the biasing magnetic field in chiral plasma.     

四磺酸基酞菁氯化铝复合二氧化硅干凝胶的制备及光学性能研究

采用溶胶凝胶法将不同掺杂浓度的四磺酸基酞菁氯化铝(AlClPcTS)植入二氧化硅凝胶基质,制备了均匀掺杂的复合干凝胶通过对二氧化硅凝胶基质和掺杂AlClPcTS后复合干凝胶孔结构的测定和对复合体系紫外可见吸收光谱的表征,证实了AlClPcTS在基质中的成功掺杂,并发现AlClPcTS同时以单体和二聚体的形式存在于复合体系中,且AlClPcTS二聚体所占比例随着凝胶化过程的进行而增大对不同AlClPcTS掺杂浓度复合干凝胶的光限幅性能进行了测试,并讨论了掺杂浓度对复合体系光限幅性能的影响,证明复合体系的光限幅性能随掺杂浓度的提高而增强.     

15波长输出的布里渊掺铒光纤激光器

多波长布里渊掺铒光纤激光器是一种新型的多波长光纤激光器,其原理是利用受激布里渊增益和掺铒光纤的线性增益,可以在常温下得到波长间隔约为0．08nm(～10GHz)的多波长输出。报道的布里渊掺铒光纤激光器,在布里渊抽运功率为1．7mW、980nm抽运功率为300mW的情况下得到稳定的15个波长(间隔～10GHz)的输出,这种激光器用作光传感器、光谱分析仪以及密集波分复用系统的光源。实验发现,输出波长的个数随着980nm抽运功率的增大而增加。另外,布里渊掺铒光纤激光器的信号功率主要来自于掺铒光纤的增益,而布里渊增益对它的影响不大。     

Coherence Measurement of White Light Emission from Femtosecond Laser Propagation in Air

Strong white light emission is observed from femtosecond laser propagation in air. The divergence angle of the white light emission is measured to be about 5mrad. Young＇s double-slits and a Michelson interferometer are used to investigate the coherence. The wavelength components of the white light emission are identified to have a good spatial coherence and a coherence time of about 0.5ps.     

MP-C60(M=Cu,Co)化合物的合成、表征及光电性能研究

卟啉和金属卟啉不仅是良好的电子给予体,而且在紫外可见光区有着非常广泛的吸收,这有利于太阳能的利用.富勒烯(C60)由于自身独特的结构而成为较好的电子受体.近年来,大量共价键连卟啉-富勒烯D-A化合物被合成与研究[1-4].通过柔性连接体形成的卟啉-富勒烯化合物有利于增加给-受体间电子的流动性,使化合物具有优良的光电转换性能[2].中间体和产物的合成见图1.1和2的合成、纯化参照文献[2].3的合成:在N2下把37.2mg对羟基苯甲醛、75.2mg2、过量灼烧的无水碳酸钾加入30mL DMF中,80°C反应8h后,甲苯和蒸馏水分液,粗产品用硅胶柱层析,甲苯淋洗,…     

反射型磁光多层膜隔离器工作稳定性的研究

与单纯的磁光晶体相比,由磁光介质与电介质周期性或准周期性排列构成的一维磁光光子晶 体能够显著增强磁光效应,可以用于实现小尺度的磁光隔离器,从而大大减小器件的尺寸. 给出更为一般的可用于求解斜入射情况下偏振光在各向异性介质中传播时的传输矩阵方法, 并用这种方法在波长为1053μm处,针对两种“三明治”型的反射磁光多层膜隔离器的 结构,具体讨论了器件应用时入射角度及工艺制作时膜层制备厚度对它们工作稳定性的影响 .发现中心磁光介质夹层较厚的结构具有膜层数目少、工作稳定性好的优点. 关键词： 光隔离器 磁光效应 一维光子晶体     

Ultracold two-component fermionic gases with a magnetic field gradient near a feshbach resonance

We study theoretically the ultracold two-component fermionic gases when a gradient magnetic field is used to tune the scattering length between atoms. For 6Li at the narrow resonance B0=543.25 G, it is shown that the gases would be in a coexistence of the regimes of BCS, Bose-Einstein condensation (BEC), and unitarity limit with the present experimental technique. In the case of thermal and chemical equilibrium, we investigate the density distribution of the gases and show that a double peak of the density distribution can give us a clear evidence for the coexistence of BCS, BEC, and unitarity limit.     

Properties of circularly polarized vortex beams

The properties of circularly polarized vortex beams in cylindrical polarization bases are studied. A circularly polarized vortex beam is decomposed into radial and azimuthal polarization. With the proper combination of vortex charge and the handedness of the circular polarization, a focal field with an extremely strong longitudinal component as well as a flat-topped profile can be obtained. The cylindrical decomposition also sheds light on the connections between orbital angular momentum and the spin of the light beams.     

多速率STFT超宽带信号瞬时频率估计研究

提出多速率短时傅里叶变换(Multi Rate Short Time Fourier Transform,MR-STFT)瞬时频率估计算法,提高了超宽带信号瞬时频率估计精度。该方法将多速率信号处理算法与短时傅里叶变换(STFT)技术相结合,兼顾采样频率和被测频率,将宽频范围进行分段采样,对分段处理结果进行拟合,构成多速率STFT算法,实现超宽带信号瞬时频率的高精度测量。论文通过对仿真信号和实测信号进行处理,研究了方法的可行性和频率估计精度,结果表明MR-STFT算法较大提高了超宽带信号瞬时频率估计精度,尤其对低信噪比的超宽带信号效果显著。     

Magnetization reversal of Fe ultrathin film on Cu(100)

The magnetization reversal of Fe/Cu(100) ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimeter with a magnet that can rotate in a plane of incidence. There occur spin reorientation transitions from out-of-plane to in-plane magnetizations in 8 and 12 monolayers (ML) thick iron films. The coercive fields are observed to be proportional to the reciprocal of the cosine with respect to the easy axis, suggesting that the domain-wall displacement plays a main role in the magnetization reversal process.