In this work we propose a simple approach to realize the direct frequency modulation of a semiconductor distributed feedback (DFB) laser. The directly frequency-modulated DFB laser (DFL) is biased by a direct current (DC) on a normal electrode along the laser cavity to define the output power. The signal current is applied on an extra short electrode placed in the center section of the DFB laser, isolated from the DC electrode. The varying of the material refractive index in the center section with the signal current introduces an effective grating phase change, thereby alters the lasing frequency. Small-signal simulation shows that a frequency modulation efficiency of 26GHz/mA from 0 to 100GHz and 17GHz/mA from 100GHZ to 200GHz can be achieved, respectively. Large-signal simulation of the waveform and eye-diagram of a frequency-shift keying (FSK) signal generated by the DFL is also performed by converting it to an intensity modulated signal through an optical slope filter.

中文翻译：

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直接调频DFB激光器的设计与仿真

在这项工作中，我们提出了一种简单的方法来实现半导体分布式反馈 (DFB) 激光器的直接频率调制。直接调频 DFB 激光器 (DFL) 由沿激光腔的正常电极上的直流 (DC) 偏置以定义输出功率。信号电流施加在放置在 DFB 激光器中心部分的额外短电极上，与直流电极隔离。中心部分的材料折射率随信号电流的变化引入了有效的光栅相位变化，从而改变了激光频率。小信号仿真表明，0-100GHz频率调制效率分别为26GHz/mA和100​​GHz-200GHz频率调制效率17GHz/mA。