半導體雷射內部光場與外部輸出之分析與模擬

Abstract

多區段半導體雷射於高速光學網路中有其多重角色，既可為雷射光源、亦可為時脈光源，可運用於波長轉換、亦可運用於時脈恢復。當作為時脈光源時，多區段半導體雷射之輸出為週期性光信號，其週期性光信號輸出是否為穩定的週期性光信號？ 本研究以二區段分佈反饋式雷射為核心，將聚焦之點為：「『二區段分佈反饋式雷射』之『內部光場變化』與『外部週期性波形光輸出變化』，於『二區段分佈反饋式雷射』之『研究框架』下，進一步探究雷射之『細部結構變化』對光輸出之『細部週期性波形變化』」。 本研究以「半導體雷射整體腔體長度」、「二端面相位改變」、「線寬增強因子」為結構參數；以「分散－Q－交換」與「模態競爭」理論基礎，模擬演算法採有限差分法分析；先與Carroll（1998）之先前研究相互比較內部光場特性，驗證模擬結果可接受性。次再以上開結構參數為調整，模擬12種情境，驗證上開結構參數的確影響了週期性光信號輸出穩定性之波形改變；另外亦驗證即使結構參數並未調整改變，即橫截面並未有異動，然非穩定的週期性光信號仍有可能發生；故改以引入信號時間序列之觀念分析，採用自我迴歸模型進行實證分析，驗證研究假設：「半導體雷射週期性光信號輸出具有時間序列自我迴歸之特性」；實證分析結果驗證自我迴歸模型之統計顯著性，即縱斷面分析具有時間序列特性。本研究最後統合橫截面分析與縱斷面分析，提出整合性的二階段分析架構，為分析週期性光信號輸出是否為穩定的週期性光信號提出系統性判斷架構。

Multi-section semiconductor laser is with multiple roles, i.e. laser source, periodic optical clock source, wavelength conversion application, and clock recovery. Being a periodic optical clock source, the output of one multi-section semiconductor laser is periodic optical signal. But, will such semiconductor laser periodic optical output be stable periodic optical signal? This report focuses on two sections distributed feedback semiconductor laser, and the research point is the internal optical field dynamics of two sections distributed feedback semiconductor laser and dynamics of output periodic optical signal. Limited to the frame of two sections distributed feedback semiconductor laser, we study the effect of output waveform dynamics because of laser structure parameter. The study take semiconductor laser cavity length, two facet phase changing, and linewidth enhancement factor as structure parameters. The dispersive-Q-switching and mode beating theory are the basis of finite difference analysis algorithm; and we first compare the internal optical field with the result of the prior art by Carroll (1998) to check the acceptance of initial simulation result. Then, based on the above three structure parameters, we tune these parameters to simulation 12 situation to verify that the above laser structure parameters affect the stability in waveform of periodic optical output. In addition, we also verify that even the structure parameters are unchanged, in other words, no cross-section dynamic, it is still possible to generate unstable periodic optical output, hence, we introduce signal time series concept, i.e. using auto-regression model to process practical analysis. Our research hypothesis: the periodic optical output signal of semiconductor lasers is with time series auto-regression. The practical result verify that the statistical significant in auto-regression model, in other words, longitudinal section is like as time series. We propose one combined analysis of longitudinal section and cross-section, which include two-step analysis architecture as the decision weather semiconductor laser periodic optical output be stable periodic optical signal.