針對不受相位光罩長度限制的製作新方法分析密波長多工多通道光纖光柵濾波器頻譜干擾之最佳化修正

Abstract

本論文提出密波長多工多通道光纖光柵濾波器頻譜干擾之最佳化修正方法。先利用其它可能引起頻譜干擾的多通道光纖光柵設計方法做初步設計，接著利用Lagrange multiplier optimization(LMO)最佳化演算法來達到降低頻譜干擾的最佳化設計。由於原先的設計已提供相當接近的折射率變化輪廓，使得利用LMO進行最佳化運算時只需微小變化原先設計的輪廓便能快速收斂至目標反射頻譜，同時此混合演算方法又能保留原先設計方法的優點，例如重疊寫入多通道光纖光柵之易於製造的特色。本論文中我們也提出一種不受相位光罩長度限制的光纖光柵製造平台構想並針對之來分析前面所設計出來的密波長多工多通道光纖光柵在實際製造上之容忍誤差。此種藉由相位光罩一段一段接續的光纖光柵製造平台，應能大大提升實際製造長度很長或是較複雜之光纖光柵的容忍誤差。

This thesis presents work on optimized spectral distortion correction of DWDM multichannel fiber Bragg grating (FBG) filters. The developed hybrid algorithm starts from some other multichannel FBG design method which may suffer from the spectral distortion and use the Lagrange multiplier optimization (LMO) algorithm for final optimization. Due to the initially close-to-optimum index modulation profile, the calculation can be fast converged to the target reflection spectra by using the LMO algorithm and the final design still retains the merits of easy fabrication. We have also proposed a new fabrication method not limited by the phase mask length and have performed the tolerance analysis for the designed DWDM multichannel fiber Bragg grating (FBG) filters based on the proposed fabrication platform. By the section-by-section connection of the phase mask, this platform should effectively reduce the errors during the UV exposure and accurately fabricate FBG devices with long length and complicated profiles.