激光熔覆铁基大厚度非晶合金表层的研究

利用激光熔覆制备了大厚度铁基非晶合金表层，非晶层厚度为0.74mm，表征非晶合金过冷液相区的ΔT(非晶转变温度及晶化温度之差)为67K。XRD、TEM与DSC分析表明表层为单相非晶。分析了非晶形成机制。

空潜信道中基于多光束阵列的二维图案传输

提出了一种利用多光束阵列在复杂散射信道中进行二维图案传输的理论模型。与传统多光束传输方案思路不同，该模型有效利用信道的强散射特性，使各光束充分扩散，在接收面形成交迭区域，成像光学系统在该区域内接收光信号并恢复各发射光束的空间位置信息，完成二维图案信息在空潜信道中的多通道传输。视在参数的引入使光束原本在两个不同折射率介质中的传输简化为仅在一种介质中传输的简单问题。实验采用直径为15mm的微透镜阵列以及长为12．65m的海水、大气信道来模拟实际信道中的强散射作用，结果表明该模型具有较好的可行性。

Two-step digit-set-restricted modified signed-digit addition-subtraction algorithm and its optoelectronic implementation

A novel, to our knowledge, two-step digit-set-restricted modified signed-digit (MSD) addition-subtraction algorithm is proposed. With the introduction of the reference digits, the operand words are mapped into an intermediate carry word with all digits restricted to the set {(1) over bar, 0} and an intermediate sum word with all digits restricted to the set {0, 1}, which can be summed to form the final result without carry generation. The operation can be performed in parallel by use of binary logic. An optical system that utilizes an electron-trapping device is suggested for accomplishing the required binary logic operations. By programming of the illumination of data arrays, any complex logic operations of multiple variables can be realized without additional temporal latency of the intermediate results. This technique has a high space-bandwidth product and signal-to-noise ratio. The main structure can be stacked to construct a compact optoelectronic MSD adder-subtracter. (C) 1999 Optical Society of America.

激光脉冲宽度对有质动力加速电子的影响

基于真空中单电子运动模型，编程计算得到了高斯激光脉冲与初始位于激光传播轴上电子的相互作用结果。不同激光参鼍条件下，得到了电子的能量增益与激光强度、焦斑大小和脉冲宽度关系。结果表明，高斯激光脉冲焦斑较大时，电子没有明显的能量增益，高斯激光脉冲焦斑太小时，电子也没有明显的能量增益。电子的能量增益有一个最佳焦斑大小。在相同激光强度下，电子能量增益的最佳焦斑大小随脉冲宽度的增大而增大，但最佳焦斑大小与脉冲宽度的比值基本上是不变的。

Ultrabroad infrared luminescences from Bi-doped alkaline earth metal germanate glasses

We report on ultrabroad infrared (IR) luminescences covering the 1000-1700-nm wavelength region, from Bi-doped 75GeO(2) 20RO-5Al(2)O(3) 1B(2)O(3) (R = Sr, Ca, and Mg) glasses. The full width at half-maximum of the IR luminescences excited at 980 nm increases (315 -> 440 -> 510 nm) with the change of alkaline earth metal (Mg2+ -> Ca2+ -> Sr2+). The fluorescence lifetime of the glass samples is 1725, 157, and 264 mu s when R is Sr, Ca, and Mg, respectively. These materials may be promising candidates for broad-band fiber amplifiers and tunable laser resources.

激光玻璃与包边玻璃的折射率匹配

从理论上详细探讨了基质激光玻璃与包边玻璃的折射率匹配与剩余反射率的关系,并从实验上验证了折射率匹配越好,吸收系数与包边玻璃厚度的乘积越大,则剩余反射率越低,从而对激光放大器中寄生振荡的抑制越好,增益也就越高。