半導體雷射之高頻電光特性

Abstract

近年來，雷射二極體已經儼然成為光通訊元件中重要的一環。他的應用廣泛，像是光碟片讀取乃至於將訊號傳輸至主機，以致於光纖通訊系統，半導體雷射都扮演著不可或缺的角色。 關於半導體雷射特性的量測方法有非常多種，其中關於高頻電性的量測可以得到許多有用的資訊。譬如，我們可以藉由量測雷射阻抗特性中獲取鬆弛共振頻率。這個方法比直接透過光學量測調變頻寬更為方便。我們也可以用雷射暫態分析來探討調變頻寬，但同樣地實驗架構也較為複雜。 在本論文當中，我們以電性的觀點切入半導體雷射的主題，並由電的特性建立半導體雷射之等效電路模型。我們也探討了高頻阻抗量測的侷限，更進一步直接透過光學量測調變頻寬，並與雷射暫態的實驗結果相互比較與分析。 此外，我們也討論了許多雷射相關的重要參數，包括二極體微分電阻，理想因子，以及載子的各種時間參數對應於電路模型上的意義。

Diode laser have become an important commercial component. They are used in a wide variety of applications ranging from the readout sources in compact disk players to the transmitters in optical fiber communication systems. There are various measurement techniques to explore different properties of laser diodes. One of them is the high-frequency electrical characterization which can provide us lots of useful information. For example, we can measure the relaxation oscillation frequency of laser diodes through impedance characterization. This technique is elegant and proves to be an easier way than direct measurement of optical modulation bandwidth. We can also investigate laser modulation bandwidth from the transient analysis, but again the experimental setup is more complicated. In this paper, we investigate the properties laser diodes throught electrical characterization and build up their equivalent circuit models. We also discuss the limit of impedance measurement and try further the direct optical measurement of modulation bandwidth. These results will be compared with those of laser transient experiments. Furthermore, we discuss various important diode parameters, such as differential diode resistance, ideality factor, and the carrier time constants, and their corresponding meaning in the circuit model.