腔內倍頻二極體激發的固態雷射，經常因為共振腔內不同縱向模態的相互耦合效應，產生綠光訊號振幅具有劇烈的擾動現象，造成了綠光雷射輸出功率不穩定，此即一般所謂的“ 綠光雜訊(green problem)”；這個問題的發生將嚴重限制此種雷射的發展與應用，因此有許多研究學者紛紛提出不同的解決方法，但是多半仍著重於設計複雜的共振腔架構。

在本論文中，首先將簡單介紹一些有關於綠光雜訊的資料文獻，並且根據文獻上所提供的rate-equation搭配實際的參數值去模擬綠光雜訊行為，除此之外，也將逐一去分析討論各個參數對於雜訊行為的影響；另外於實驗的部份，我們將利用波長為808nm的半導體雷射去激發Nd:YVO4/KTP的黏合晶體產生倍頻綠光，並且於示波器上觀察綠光訊號，而為了消除其綠光雜訊，我們在不改變共振腔結構的前提下，設計了一個特殊的激發光源電路，希望這電路能夠干擾或是減低模態的耦合效應，同時消除綠光雜訊，最後將利用Fabry-Perot光譜分析儀去觀察這特殊電路對於基頻光模態數的影響。

根據模擬的結果發現，當模態的極化方向分佈不同時，其綠光雜訊的狀態也不ㄧ樣，且雜訊並非皆為雜亂無章，在某些參數值的情況下將會呈現週期性的狀態，實驗上所觀察到的綠光雜訊也確實呈現週期性的變化，而在利用本論文所設計的特殊電路之後，將明顯得逐漸消除綠光雜訊，使得綠光訊號達到穩定的輸出，同時發現其基頻光的模態數目也將逐漸減少，甚至能夠達到單一模態操作。

Due to the coupling between longitudinal modes in the intracavity doubled diode-pumped solid-state(DPSS) laser, such as Nd doped YAG or YVO4, large amplitude fluctuations have been observed in the green output. This phenomenon knows as the “Green Problem”, and it seriously restricts the development and applications of intracavity doubled DPSS laser. A lot of researchers put forward different solutions to the green problem. However, they mostly focused on designing a complicated structure of the resonance cavity.

In this thesis, we illustrate the green problem based on previous works, mostly done by Baer[2] and James[7], and obtained the green noise simulation from the rate-equations. In addition, we discuss the parameters which affect the behavior of green noise. In the experiment, we used an 808nm laser diode to pump a Nd:YVO4/KTP crystal pair. The green noise was observed by photodiode. To eliminate the green noise, we designed an electronic circuit to modulate the laser diode. The number of the longitudinal mode by the Fabry-Perot interferometers was also measured.

The results show that the green noise was suppressed and the laser operated in single mode at high modulation frequency.

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