利用自發脈衝光引起光注入鎖模之二段式邊射型雷射高頻特性研究

Abstract

本論文中我們研究利用回饋引起光注入鎖模的二段式可調式雷射特性，發光波長為1.55微米，我們使兩顆緊鄰的相同的雷射元件中央位置準確地利用聚焦離子束與電子束蝕刻出具有特定寬度深度的空氣柱，此雷射一出光端面為高反射層而另一端面為抗反射層，我們藉由共振腔光場強度的模擬結果可知主要由空氣柱的深度變化導致由主雷射的共振腔產生的雷射光注入到副雷射共振腔的注入比例不同，此外，主副雷射之間的電流分佈也隨著空氣柱的深度有所不同。我們基於光注入鎖模理論，在一個穩定的光注入鎖模範圍內，顯示出分別在有外部注入光與無外部注入光源的情況下做相對雜訊的量測與模擬，我們觀察到在有外部注入光的情況下，雷射共振腔的共振頻率可以大幅提升。理論上若使得主雷射的光注入比例越大，則共振頻率峰值可增加至10 GHz以上，另外利用此技術可使得相對強度雜訊能夠有效的降低，在本論文中將由特定空氣柱深度的條件設定以及鎖模情況下，改變主雷射的注入光比例使得相對強度雜訊峰值能夠至少達至20 GHz。由此技術可使雷射大幅增加頻寬，頻譜分析與探討將在本論文中進行研究與討論。

In this thesis,we study the characteristics of the 1.55μm two-section self-feedfack laser with injection-locking technique.We fabricate an air gap with a specific width and depth in the middle of the two single-mode laser side by side with the focus ion beam system. The laser device has an high-reflection facet and an anti-reflection one on the other side. From the wave intensity simulation, we know that the injection ratio from the master laser (ML) to the slave laser (SL) will differ at different depths. Besides, the current distribution in the two-section cavity will also differ because of the different depths. Based on the optical injection-locking theory, we present the device structure about 1.55µm two-section edge emitting laser、the relative intensity noise (RIN) measurement of the device with light injection and without light injection, and the simulation results of RIN spectrum .We can observe that the resonance frequency increase largely under a external injection light condition. Theoretically if we increase the injection ratio, the resonance frequency can be up to 10 GHz at least, and relative intensity noise can reduce effectively. In this thesis fixing some gap depths, we change the injection ratio from ML, and we can enhance the RF frequency up to 20 GHz at least under injection-locking condition. With the technique, we can increase the laser modulation bandwidth.