半导体光电, 2016, 37 (2): 165, 网络出版: 2016-05-11
光纤光栅外腔半导体激光器的线宽特性研究
Study on Linewidth Characteristics of Fiber Grating External Cavity Semiconductor Laser
半导体激光器 外腔 等效反射率 线宽压窄因子 窄线宽 semiconductor lasers external cavity effective reflection coefficient linewidth compression factor narrow linewidth
摘要
通过构建外腔半导体激光器的等效腔模型,并在修正的肖洛-汤斯线宽公式中引入外腔压窄因子,系统模拟了光纤光栅外腔半导体激光器的电流阈值特性和线宽特性。以等效腔模型为基础,综合考虑外腔压窄因子,利用修正后的肖恩-汤斯公式,使用Matlab对外腔激光器的阈值和线宽特性进行了系统的模拟。模拟结果表明:通过增加外腔反射率,可有效增加光子寿命并降低阈值载流子浓度,进而获得较低的阈值电流,对于0.81的外腔等效反射率,阈值电流低至3.83mA;通过增加外腔反射率、耦合效率和外腔长度,可显著压窄线宽至千赫兹量级;此外,合理限制增益芯片尺寸也会压窄线宽。激光器工作电流为60mA时,当外腔光栅反射率由0.1提高至0.9可使阈值电流由9.04mA降低至4.01mA,线宽由95.27kHz降低至1.34kHz;当外腔长度由2cm增加至6cm时,激光器线宽由3.20kHz降低至0.36kHz。
Abstract
A brief model was used in this letter to perform the linewidth property by introducing the effective reflection coefficient Reff. And then the external cavity linewidth compression factor was also considered to simulate the linewidth properties of the Fiber-grating external cavity semiconductor laser according to the Schawlow-Townes formula revised by Lax.. The simulation results show that the threshold current reduces from 9.04mA to 4.01mA with the grating reflection (Rext) increasing from 0.1 to 1. Besides that, it can be seen that the linewidth reduces from 95.27kHz to 1.34kHz while the Rext increasing from 0.1 to 1 when the laser operates at 60mA. What’s more, the linewidth can be reduced from 3.20kHz to 0.36kHz by increasing the external cavity from 2 to 4cm at the same current. Furthermore, more discussion about other parameters can be reduced to 3.83mA with the Reff increasing to 0.81. This is because that the higher the Reff, the longer the photon life, which leads to smaller threshold carrier density. The linewidth can be condensed to kHz magnitude by increasing the Reff, coupling coeffient C0 and the length of the external cavity.
刘大鹏, 陈超, 秦莉, 张星, 陈泳屹, 曾真, 宁永强. 光纤光栅外腔半导体激光器的线宽特性研究[J]. 半导体光电, 2016, 37(2): 165. LIU Dapeng, CHEN Chao, QIN Li, ZHANG Xing, CHEN Yongyi, ZENG Zhen, NING Yongqiang. Study on Linewidth Characteristics of Fiber Grating External Cavity Semiconductor Laser[J]. Semiconductor Optoelectronics, 2016, 37(2): 165.