光子晶體雷射之研究

Abstract

我們成功地利用電子束微影系統與活性離子乾式蝕刻的技術在砷化鎵基板上製作出二維光子晶體，並且將二維光子晶體波導與邊射型雷射整合在一起，這樣的雷射結構具有單一縱模的特性，邊模抑制比可以達到14dB，並且在大範圍的電流驅動下都可以維持一定程度的邊模抑制比。 本論文提出共振腔耦合的模型來解釋雷射特性，我們將光子晶體雷射視為兩個共振腔的組合，一為光子晶體波導所形成的共振腔，一為Fabry-Perot共振腔，雷射的輸出頻譜是兩個共振腔耦合所產生的結果；除此之外，為了改善大面積雷射的橫向模態，我們利用光子晶體來降低雷射輸出端的反射率，藉由提高雷射的臨界增益來抑制高階橫向模態的產生。 文中將從光子晶體雷射的L-I曲線、輸出頻譜、近場發光圖形以及雷射的變溫特性等對光子晶體雷射做詳細的探討，並且與傳統大面積雷射做比較。

We have successfully fabricated 2-D photonic crystals on GaAs wafer with e-beam lithography and reactive ion etching(RIE). With this technique, 2-D photonic crystal waveguides were integrated with edge emitting lasers, which demonstrated single longitudinal mode with side mode suppression ratios (SMSR) of 14dB and could maintain such SMSR value over a broad injection current range. In the thesis, we adopted coupled-cavity theory to explain experimental results of the photonic crystal laser. In this theory, the laser was treated as two cavities. One was the Fabry-Perot cavity and the other was the photonic crystal waveguide. The coupling of the two cavities results in the photonic crystal laser’s spectrum. Moreover, with the proper design of the photonic crystals, the threshold gain of high order lateral modes was enhanced. Thus, high order lateral modes of the laser were inhibited and the near field pattern of the laser was improved. We discussed experimental results of the photonic crystal laser through L-I curve, output spectrum, near field pattern, and the temperature dependence, and compared these properties with broad area lasers in this thesis.