半導體雷射在受到大量同調光回饋的影響時，將導致雷射產生同調崩潰的現象，而此現象將嚴重降低半導體雷射在應用上的效能。本研究的目的是企圖用正交偏振光回饋，壓制半導體雷射同調崩潰的產生進而消除雷射輸出的雜訊。

實驗中，我們先探討半導體雷射在同調崩潰時的特性。我們將Hitachi HLP 7806G的半導體雷射的工作電流設為63.9 mA，溫度為21.9 ℃，並將-11 dB的同調光回饋至雷射共振腔中，我們發現雷射從原本的單縱模狀態變成線寬非常寬的多模振盪，同時在電訊號頻譜分析儀上所測量出來的相對雜訊強度也上升了約15 dB，此時雷射所呈現出的現象，即是同調崩潰狀態。

實驗結果顯示，當-16 dB和-23 dB的正交偏振光同時回饋至雷射共振腔中時，確實能有效壓制雷射的同調崩潰狀態，使其變回十分穩定的單縱模輸出，此結果將有助於提升半導體雷射在應用上的價值。論文中也有討論許多相關實驗的結果，藉以加強說明正交偏振回饋光和半導體雷射的交互作用。

The coherence of a semiconductor laser subjected to a coherent optical feedback of greater than -30 dB will collapse, causing the laser’s performance in many applications to be severely degraded. This research investigated the feasibility of suppression the coherence collapse with orthogonal-polarization optical feedback.

In the experiments, we first studied the characteristics of coherence collapse state of semiconductor laser. Under an operational condition of 63.9 mA, 21.9℃ and -11 dB of coherent optical feedback, a Hitachi HLP 7806G semiconductor laser would be conducted from its solitary single-mode state into a multimode oscillation state with a very broad linewidth. At the same time, the relative intensity noise measured from the RF spectrum analyzer drastically raised about 15 dB.

When a -16 dB and a -23 dB orthogonal-polarization optical feedback were fed back into the laser’s cavity. The coherence collapse could be effectively suppressed, while the laser was conducted back to its solitary single-mode state stably. This result will greatly increase the application of the laser. Some experiments were also reported to explore the interaction between the laser and the orthogonal-polarization feedback light.

致謝辭
中英文摘要
目錄
圖表目錄

第一節 簡介

第二節 半導體雷射的同調崩潰

第三節 實驗系統介紹

第四節 實驗結果及討論

第五節 結論

參考資料

附錄

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