多次外光反馈下垂直腔面发射激光器非线性动态特性理论研究

Theoretical Study on Nonlinear Dynamics of Vertical-Cavity Surface-Emitting Laser with Multiple External Optical Feedbacks

在SIMULINK平台下建立了垂直腔面发射激光器(VCSEL)动态仿真模型,利用该模型对多次外光反馈下垂直腔面发射激光器的非线性行为进行了研究。结果表明,短外腔时,光子密度随外腔长呈周期为半激射波长的余弦关系;长外腔时,随外腔长增加,垂直腔面发射激光器依次经历混沌、多周期、倍周期和单周期区域,增大外腔反射率时同样存在这些非线性区域,但出现顺序相反。进一步得出:考虑单次反馈时由于忽略了占有较多能量的高次反馈导致上述非线性效应偏弱;增大自发辐射因子或减小线性展宽因子可抑制系统的非线性行为。

The model of the vertical-cavity surface-emitting laser (VCSEL) is established using SIMULINK and the nonlinear behaviors of VCSEL with multiple external optical feedbacks are studied using this model. For short external cavities, the photon density shows periodic cosine undulation along the external cavity length whose period is equal to half of the lasing wavelength; for relatively long external cavities. VCSEL undergoes the regions of chaos, multiple, double and single period orderly with increasing the length of the external cavity, however, these regions emerge contrarily with increasing the external cavity s reflectivity. If only the first feedback is taken into account, the nonlinearity is weaker than the multiple feedbacks case due to neglecting the high-order feedbacks that own a lot of energy. It is also shown that the nonlinear behaviors can be constrained by increasing the spontaneous emission factor or decreasing the linewidth broadening factor.