under under the law 根据法律。 under age 未成年。 under sb.'s hand and seal 经某人签名盖章。 under arms 武装着,手执武器。 under avow 发过誓,在誓言下。 under favour 如果允许(这样说)的话〔多作插入句〕。 under fire 在弹雨下,冒着炮火 (land under fire 在炮火下登陆)。 under foot 地上 (It was wet under foot 地上潮湿);在脚下(踩着)。 under night 〔苏格兰语〕 在夜间。 under one's breath 小声,低声。 under sb.'s (very) eye 在某人眼皮底下,显而易见。 under the line 【航海】在赤道下。 with a good meal under one's belt 饱餐一顿。 adv. 1.在下,从属着,服从着。 bring under, get under, keep under 等〔参看各该动词条〕。 The ship went under. 船下沉了。 2.在下文中。 See under for further information. 更详尽资料见下文。 3.少于,低于。 five dollars or under 五美元或五美元以下。 adj. 1.下面的,下部的 (opp. upper);附属的;从属的。 2.较次的;低劣的。 3.过少的,过小的,不足的。 the under lip 下唇。 under servants 仆役的下手。 under grazing 轻度放牧。
In succession , the theory of chirped - pulse amplifier system is given in detail , firstly , studying from designing experimental light road and optical components to theoretical analysis , we par ' tly finished the system by ourselves . about ultr a - shoft pulse with a pulse - width of 9 . 8f s and output power of 650mw and band - width of about l 20nm is output from oscillator source , secondiy , the stretching capacity of single grating four - pass stretcher is measured using abcd matrix combining collins function , and the effect of relativ e parameters to the streching ratio is also simulated . thirdly , a new type of disjunctional frequency moduiating function is provided according to the gain - narrowing and gain - saturation which are appeared in the co urse of amplification , under modulating the two effects are both controlled on some e xtent , fourthiy , the effect of ase that is often ignored by people is analyzed and the resolving methods are also given 从光路、光学元件的自行设计到理论分析计算,初步建立了一台实验系统;采用abcd矩阵法结合collins公式计算了四通式单光栅展宽器的展宽量,并模拟了相关参数对展宽比的影响,对实验具有指导意义;评价了再生放大器和多通放大器的优缺点,对放大过程中通常忽略的放大自发辐射现象( ase )进行了分析,并提出了相应的解决方法;针对放大过程中出现的增益窄化和增益饱和现象,对输入种子脉冲提出了一种新的分段频率调制函数,实现了对增益窄化效应和增益饱和效应的共同抑制;提出了系统的材料(包括放大介质和光路中的普通介质)正是融合高阶色散的来源。