(双稳外腔)LD分析中扰动近似的有效性研究

在两种不同调制(增益和损耗调制)情况下,对半导体激光器(LD)速率方程组的扰动近似处理有效性进行了分析.结果表明,在电流(或增益)调制情况下,扰动近似法所忽略的二阶小量在量级上确实与保留的一阶小量的平方相当;在损耗调制的情况下,系统变化前后的阈值载流子密度不同,被忽略的二阶小量可能会达到与一阶小量可比拟的程度.以可调谐双稳外腔半导体激光器(ECLD)为例,指明了在损耗调制下,扰动近似分析可能会失效.

Validity of perturbation approximation in bistable external cavity LDsLu Yang,Cheng Jianguo,Li Dayi

Studies have been made on the validity of perturbation approximation when analyzing the rate equations of semiconductor lasers respectively subject to small gain and loss modulations.It is found that for a current or gain modulated diode laser,the neglected second order small quantity in the perturbation method is comparable to the square of the retained first order small quality.For a loss modulation where the threshold carrier density may change,the neglected term may become comparable to the retained first order small quantity.Taking an external cavity laser diode(ECLD) as an example,calculations indicate that the perturbation analysis may become invalid under loss modulation.