we have to distinguish between the propagating modes with real valued β, and the evanescent modes with imaginary β. 我們必須分別考慮具有實數(shù)的導(dǎo)模和具有虛數(shù)的消失模。
< uk > we have to distinguish between the propagating modes with real valued , and the evanescent modes with imaginary . < / uk > < uk >我們必須分別考慮具有實數(shù)的導(dǎo)模和具有虛數(shù)的消失模。 < / uk >
The long period fiber gratings ( lpfg ) have been chosen to be the filters finally after comparing several filters . the specific loss could be achieved by the coupling between two co - propagating modes in lpfg Lpfg利用光纖內(nèi)同向傳輸模式之間的耦合,把正向傳輸?shù)幕D芰坑羞x擇性的耦合到其它正向傳輸?shù)哪J街?實現(xiàn)選擇性損耗。
The term of mode - filtered light refers to the observation that light initially propagating down an optical fiber can be decoupled from that fiber by increasing the cladding ri at the core / clad interface with a permeating analyte , thus changing the allowable propagating modes within the fiber , resulting in a continuous and nearly linear increase in mode - filtered light with increasing cladding ri 所謂模式濾光,是指分析對象進(jìn)入光纖包層引起光纖芯包界面的折射率增加,導(dǎo)致光纖內(nèi)的部分傳導(dǎo)模不滿足傳導(dǎo)條件而從光纖的包層中側(cè)漏出來的光學(xué)信號,它與包層折射率的增量在一定條件下線性相關(guān)。