非即变相位共轭反馈对半导体激光器动态特性的影响

从四波混频产生相位共轭的物理原因出发，定义了相位共轭镜（PCM）的响应时间．建立起非即变相位共轭反馈条件下半导体激光器的外腔模型。以响应时间及频率失调为参变量，对其分岔及噪声等动态行为进行数值分析。结果表明，不考虑噪声影响时，增加相位共轭镜响应时间会使混沌带出现的次数和范围得到较大的抑制，当响应时间增大到1．5ns时，混沌带消失，半导体激光器保持稳定的单周期状态；考虑噪声影响后，随若响应时间的相对强度噪声（RIN）可减小几dB甚至十几dB，产生突变需要的反馈量也增大一个数量级以上，且其频谱的峰值向高频方向移动；另外，由于共轭反馈引起的频率失调低于半导体激光器激射频率3个数量级以上．它只对分岔特性有影响．对相对强度噪声的影响几乎为零。

The Influence of Non-Instantaneous Phase Conjugate Optical Feedback on the Dynamics of Semiconductor Laser

Based on the physical origin of phase conjugation generated by four wave mixing,the response time of phase conjugate mirror is defined and the external cavity model for laser diode under non-instantaneous phase conjugate optical feedback is set up.Numerical analysis is given to discuss the influence of response time and frequency detuning on the characteristics of bifurcation and noise.The results indicate that the numbers and the range of chaotic bands can be restrained greatly by increasing the phase conjugate mirror's response time when the influeme of noise is considered.When the response time reaches 1.5 ns,all the instabilities of laser diode are suppressed.If noises considered,the intensity of relative intensity noise decreases by several dB or even tens dB with the increase of response time and its spectrum peak moves to higher frequency,the feedback rate for coherence collapse also increases by one order.Since the frequency detuning is smaller compared to laser diode lasing frequency by more than three orders of magnitudes,it only influences the bifurcation diagram and almost have no influence on relative intensity noise.