We have found a fine structure in the frequency dependence of modulation efficiency of a diode laser (DL) with a strong selective optical feedback. The FM response of an extended cavity diode laser (ECDL) to the microwave current modulation has two peaks whose frequencies are close to the intermode frequency of the laser longitudinal modes. The frequency splitting of the peaks depends on the power of laser radiation and on the difference between the frequency of operating ECDL mode and the frequency of the closest DL mode. We have observed similar splitting in AM noise spectra with the same type of dependencies on power and aforementioned frequency detuning. The peculiarity of the AM noise spectrum has been observed and explained previously by nonlinear interaction of fields in the active region of a DL that results in the frequency splitting of the modes. This dynamic splitting of the laser cavity modes explains the specific features of the modulation characteristics.

中文翻译：

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扩展腔二极管激光器的调制特性和动态模式分裂

我们已经在具有强选择性光反馈的二极管激光器 (DL) 的调制效率的频率依赖性中发现了精细结构。扩展腔二极管激光器 (ECDL) 对微波电流调制的 FM 响应有两个峰值，其频率接近激光器纵模的模间频率。峰值的分频取决于激光辐射的功率以及操作 ECDL 模式的频率与最接近的 DL 模式的频率之间的差异。我们在 AM 噪声频谱中观察到类似的分裂，对功率和上述频率失谐具有相同类型的依赖性。AM 噪声频谱的特性之前已经通过导致模式分频的 DL 有源区域中场的非线性相互作用进行了观察和解释。激光腔模式的这种动态分裂解释了调制特性的具体特征。