近场强度分布对线性相位反演算法复原效果的影响

利用数值仿真的方法详细的分析了近场强度分布对线性相位反演算法复原效果的影响.对近场强度分布分别为倾斜、环形和高斯随机型的情况下的复原结果与光强均匀时的复原结果进行对比,结果表明像倾斜型这种大部分为奇函数的近场强度分布对复原效果的影响比较恶劣;而像环形、随机型这样的偶函数或大部分为偶函数的近场强度分布对复原效果的影响则不...     

Experimental demonstration of single-mode fiber coupling using adaptive fiber coupler

Coupling plane wave into a single-mode fiber(SMF) with high and steady coupling efficiency is crucial for fiberbased free-space laser systems, where random angular jitters are the main influencing factors of fiber coupling. In this paper, we verified a new adaptive-optic device named adaptive fiber coupler(AFC) which could compensate angular jitters and improve the SMF coupling efficiency in some degree. Experiments of SMF coupling under the angular jitter situation using AFC have been achieved. Stochastic parallel gradient descent(SPGD) algorithm is employed as the control strategy, of which the iteration rate is 625 Hz. In closed loop, the coupling efficiency keeps above 65% when angular errors are below 80 μrad. The compensation bandwidth is 35 Hz at sine-jitter of 15 μrad amplitude with average coupling efficiency of above 60%. Also, experiments with simulated turbulence have been studied. The average coupling efficiency increases from 31.97% in open loop to 61.33% in closed loop, and mean square error(MSE) of coupling efficiency drops from 7.43% to 1.75%.     

大气湍流像差对空间零差二进制相移键控相干光通信误码性能的影响

通过研究不同大气湍流条件下的系统误码率(BER)来说明大气湍流引起的波前畸变给零差二进制相移键控(BPSK)相干光通信系统带来的恶劣影响。结果显示,大气湍流引起的像差可以独立于系统信噪比(SNR)作用于相干光通信系统,导致误码出现。即使在SNR无限大的情况下,当接收光信号的波面峰谷值(PV)大于一个波长后,就容易出现误码;并且随着SNR的降低,对波面PV的要求更加严格。另外,大气湍流引起的光强起伏和相位畸变会导致相干混频效率急剧下降,从而增加系统误码率。     

4-甲基-3-乙酰基-2-杂环-2H,3H-苯并[f]-1,5-硫氮杂衍生物的合成、抑菌活性及副反应的研究

以含不同取代基的杂环醛和乙酰丙酮为原料,经三步反应合成了一系列新型的4-甲基-3-乙酰基-2-杂环-2H,3H-苯并[f]-1,5-硫氮杂衍生物3a～3l,产物的结构经1H NMR,IR,MS和元素分析确证,且通过1H NMR测试,发现目标化合物存在着烯胺型和亚胺型结构的互变.测定了目标化合物的抑菌活性,抑菌结果为杂类化合物的结构与抑菌的关系提供了启示.同时,确定了目标化合物3h发生分解反应时主要副产物的结构,提出了其可能的生成机理.     

4-取代苯基-1,5-苯并硫氮杂-2-甲酸的合成及抑菌活性

合成了七元环的杂化合物2a~2k,并发现化合物2a~2k会向其同分异构体六元环内酰胺3a~3k转化.化合物2a~2k的结构通过红外光谱(IR)、核磁共振波谱(NMR)、质谱(MS)和元素分析确证.初步的抑菌活性测试结果表明,化合物2a~2k对白色念珠菌、标准新生隐球菌、临床新生隐球菌、大肠杆菌和枯草牙孢杆菌均有较好的抑菌活性,而六元环内酰胺3a~3k对所测菌种没有活性.实验还测定了部分混合物(2a~2e和3a~3e)的抑菌活性,结果表明化合物2a~2e和3a~3e混合物的抑真菌效果比单一的化合物2a~2e要好,化合物3a~3e的存在增强了化合物2a~2e的抑菌活性.     

Experimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber couplerExperimental demonstration of single-mode fiber coupling using adaptive fiber coupler

Coupling plane wave into a single-mode fiber （SMF） with high and steady coupling efficiency is crucial for fiber- based free-space laser systems, where random angular jitters are the main influencing factors of fiber coupling. In this paper, we verified a new adaptive-optic device named adaptive fiber coupler （AFC） which could compensate angular jitters and improve the SMF coupling efficiency in some degree. Experiments of SMF coupling under the angular jitter situation using AFC have been achieved. Stochastic parallel gradient descent （SPGD） algorithm is employed as the control strategy, of which the iteration rate is 625 Hz. In closed loop, the coupling efficiency keeps above 65% when angular errors are below 80/3tad. The compensation bandwidth is 35 Hz at sine-jitter of 15 ~rad amplitude with average coupling efficiency of above 60%. Also, experiments with simulated turbulence have been studied. The average coupling efficiency increases from 31.97% in open loop to 61.33% in closed loop, and mean square error （MSE） of coupling efficiency drops from 7.43% to 1.75%.