Secondly, basing on the theory of on - off gain of small signal, the raman gain coefficient for frequency shift between 0. 5 and 20 thz of standard sigle mode optical fiber is measured by pump - probe method through a super luminescent diode ( sld ) as a broadband small signal probe source. thirdly, numerical simulation analysis of gain characteristic of raman fiber amplifier for c band wdm signal light is made according to the raman gain coefficient of the fiber measured before through target and four rank runge - kutta method. at the invariability of wavelength and maximum power of each of two pumps, schematic of powers of two pumps for best flatness on c band wdm optical gain was found out, at the same time, the factors of resulting in gain saturation is analyzed, too
本文首先應用經典的電磁理論對
拉曼光纖放大器的工作
機制進行了分析，然後，根據小信號理論推導出的開關增益求出了光纖
拉曼增益系數的表達式，採用泵浦-探測波的方法，利用超
輻射激光二極體（ superluminescentdiode簡稱sld ）作為探測光源，測量了所用標準單模光纖頻移為0 . 5 - 20thz的
拉曼增益系數，之後根據所測得的光纖的
拉曼增益系數譜對應用該類光纖構成的放大c波段wdm光信號的
拉曼光纖放大器的增益特性採用打靶法和四階龍格- - -庫塔進行了數值計算，在給定了兩個泵浦光源的波長和最大功率后，找出了反向泵浦情況下使c波段wdm光源增益最平坦的兩個泵浦的各自最佳功率，同時也分析了導致信號光飽和的原因。
" you can never say that something is without risk, but at least we can say that there is no scientific evidence for a causal association between the use of cellular phones and cancer, " said lars - erik paulsson, a radiation expert with the agency
研究所的一位輻射專家拉爾斯-埃里克保爾松指出： "不能肯定這使用手機絕對沒有危險性，但至少我們現在可以說用手機和得癌癥之間沒有必然的直接聯系。
