分布布喇格反射镜的反射特性

采用等效法布里珀罗(FP)腔方法对分布布喇格反射镜(DBR)的特性进行了研究,计算并讨论了上下两层DBR结构非对称模型反射率的变化.设计了DBR反射镜的反射谱中心波长为850nm的结构.随着DBR周期数的增加,腔反射率峰值逐渐增加.上下两层DBR反射镜的厚度由反射率和中心波长决定.实验表明,下DBR的周期数为30对左右,上DBR的周期数为20对左右,易实现激光输出.非对称的双层DBR的反射特性表明理论计算与实验结果基本一致.

Reflectance Characteristics of Distributed Bragg Reflector

The reflectivity characteristics of Distributed Bragg Reflector (DBR) are described by an equivalent F-P cavity method.The DBR structure is grown by MOCVD.The GaAs buffer layer is grown on the n-type GaAs substrate,its thickness is 500 nm.The DBRs is consisted of Al_0.12Ga_0.88As/Al_0.9Ga_0.1As and the optical thickness of each layer is of quarter wavelength.The top DBR is consisted of 22 pairs,and the bottom DBR is consisted of 34 pairs.The active region is consisted of three undoped multiple quantum wells structure of GaAs/Al_0.3Ga_0.7As.The p-type dopant is carbon and the n-type dopant is silicon. The reflectivity of DBR with asymmetric structure is calculated and discussed.The structure of 850 nm center wavelength of the DBR reflectance spectrum was designed.The thickness of DBR structure was determined by its reflectivity and center wavelength. The experimental results indicated that this is an effective method for the optimal design of DBR.As a result in practice,it is easy to output laser when the periodicity of reflector in bottom DBR structure is about 30 pairs and periodicity of reflector in top DBR structure is about 20 pairs. Be compared with the experimental results,it is found that the simulative results are similar with the experimental results.It indicates that the simulative results are reliable and it can also be used for simulating some others.The experiences indicated that the simulation is an important guideline for developing and fabricating the DBR.