一种基于热补偿电流的大功率VCSEL模型

A Theoretical Model of High Power VCSEL Based on the Thermal-offset-current

基于激光速率方程并加入了热补偿电流,建立了一种用于分析大功率垂直腔面发射激光器(VCSELs)输出特性(P-I)的模型。先测得已知温度下的P-I特性,根据实验数据,利用阈值电流和温度的关系和Gao等人的方法得到a参数和其它参数。把所得参数代入模型,可以获得所需温度下的P-I特性。从模拟结果可以看出,不同温度下,模拟结果与实验结果吻合的非常好,而不考虑热补偿电流时差别很大,从而证明了该激光器模型的有效性;同时,从有源区温度和电流关系曲线可以看出,有源区随着电流增加温升很快,进一步证实了我们研究温度影响的重要性。

Vertical cavity surface emitting lasers （VCSEL＇s） are widely used in optical communication due to their single-longitudinal-mode operation, circular output beams, suitability for monolithic two-dimensional （2- D） integration, and compatibility with on-wafer probe testing. In recent years high power output has been realized by increasing the size of the emission window or by high densely integrating VCSEL array. Accompanying the increase of the output power, the performances such as temperature stability, conversion efficiency, and mode distribution are often deteriorated by the non-uniform distribution of carriers across the active region and the self-heating inside the device. Self-heating results in considerable differences between the operating performances under continuous wave and pulsed operation. Thermal roll-over of the output power with current is observed under continuous wave, which limits on the further increase of lasing power. A theoretical model based on laser rate equation is presented to simulate the output performance of high power VCSEL. In this simulation, thermal offset current is introduced to compensate the threshold current between room temperature and operating current. Thermal characteristics parameter is obtained from the dependence of the output power on the current at different temperature. Other parameters are extracted using the method of Gao et al. The dependence of P and I at certain ambient temperature was calculated according to the model parameters, and it shows a good consistent between the theoretical and the experimental results in the temperature range from room temperature to 100℃. In addition, the relationship between temperature and current indicates sever temperature increase in the active region.