Nonlinear Crosstalk Suppression in WDM-SCM Systems

The mechanism of nonlinear crosstalk in WDM-SCM fiber communication systems is investigated. Then the crosstalk suppression method of complementary modulation of twin carriers is introduced and discussed. Aiming at the limitation of this method, a new method named symmetric carrier complementary modulation is presented, and it has shown satisfactory effect in crosstalk reduction.     

An airborne diode laser spectrometer for the simultaneous measurement of H2O and HNO3 content of stratospheric cirrus clouds

We describe a tunable diode laser spectrometer for the in situ simultaneous detection of the nitric acid and the water vapour by means of high resolution absorption spectroscopy on rovibronic lines, using a single laser emitting in the mid-infrared (5.8 μm) and a multipass cell. The instrument was designed to be installed on a high altitude aircraft, as a part of a composite payload for atmospheric aerosol studies. The instrument design criteria are discussed and the expected performances are compared with results of laboratory and field operation. Due to the high chemical activity of HNO₃, that makes difficult to use a reference cell, a fast sweep detection of direct absorption was used for the measurement. An absorption sensitivity of about 2×10⁻⁴ was achieved with an integration time of 2.5 s, corresponding to a concentration of about 4 ppb of HNO₃ in the cell and 0.1 ppb in the external aerosol. The data acquisition and processing techniques, based on the full molecular lineshape fitting are also shown and discussed, including some examples of the data acquired during the scientific flights.     

电子碰撞亚稳态氦电离截面的计算

在电子和激发态原子散射的物理过程中，靶的连续态是非常重要的通道，我们使用等价局部光学势模型计算了从电离阈值到２００ｅＶ能量范围的氦的２３Ｓ亚稳态的电离截面，并同实验结果作了比较。     

激光旋光法监测谷氨酸钠浓度的实验研究

味精精制过程中的谷氨酸钠溶液浓度需控制在一定的范围。本文报道一种可用于在线监测谷氨酸钠浓度的双光束激光旋光差动式检测法,并对该方法的可行性进行了初步的实验研究。实测结果表明本方法有较好的实用性。     

二维光学神经网络自由空间互连结构设计

本文分析了以透镜阵列元件建立空间互连通道的光学神经网络中神经元数的理论极限.为了提高网络中的神经元数,我们提出了一种并行结构设计,该结构克服了小透镜成象中的离轴象散的影响,提高了系统的光能利用效率,同时降低了系统中的对位精度误差,提高了互连运算精度.     

Kinetic energy oscillations in annular regions of ultracold neutral plasmas

A study of ion equilibration in annular regions of ultracold strontium plasmas is reported. Plasmas are formed by photoionizing laser-cooled atoms with a pulsed dye laser. The experimental probe is spatially-resolved absorption spectroscopy using the ²S_1/2-²P_1/2 transition of the Sr⁺ ion. The kinetic energy of the ions is calculated from the Doppler broadening of the spectrum, and it displays clear oscillations during the first microsecond after plasma formation. The oscillations, which are a characteristic of strong coulomb coupling, are fit with a simple phenomenological model incorporating damping and density variation in the plasma.     

Relative densities of hydrogen ion species in a hollow cathode glow discharge

Highly resolved Doppler shifted peaks of the hydrogen Balmer lines, resulting from charge exchange of H⁺, H₂⁺, and H₃⁺ with an H₂ gas target, were obtained without the need for a deconvolution procedure. This enabled the unambiguous determination of the chemistry of these hydrogen species in the units of mTorr pressure range. This was obtained from a gaseous discharge using a biconical hollow cathode that yielded a well collimated and monoenergetic beam.     

光互连中二元计算全息算法的研究

二元计算全息(BCGH)是光学信息处理中一个重要元件,其在动态光互连中被广泛使用.为了更好地在光互连中应用BCGH,本文设计改进了二元计算全息的选代算法,比较了几种内能函数下的迭代算法所设计的BCGH,对其象质的不同指标进行了分析.结果表明,用迭代搜索算法是光互连应用中设计BCGH的一种较理想算法.     

一维大气边界层光学折射率结构常数数值模式的敏感性分析

 提出了一种大气光学折射率结构常数的数值模式。通过敏感性分析发现，对折射率结构常数有显著影响的参数是：一年中的不同日期、土壤的热容量和含水量、雪地和水面上、云量等，风速大小几乎对折射率结构常数没有什么影响。     

EPR and optical studies on transition metal doped LiRbB4O7 glasses

Electron paramagnetic resonance and optical investigations of copper and chromium doped LiRbB₄O₇ glasses are carried out. From the results and discussions, it is predicted that both the transition metal ions exhibit octahedral environment. In the case of Cr³⁺, the site symmetry is near octahedral, whereas in the case of Cu²⁺, it is tetragonally distorted octahedral environment. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. The bonding parameters are suggesting ionic.