Transient mode competition in directly modulated DFB semiconductor laser

A new effect of transient mode competition in directly modulated DFB laser based on equivalent phase-shift （EPS） technique is presented and studied. Since there are multi-order reflections in EPS structure and if the 0th order subgrating is properly de- signed, the transient lasing of 0th order will occur during the rising time of the injection current. As a result, transient mode competition between -lst order （main mode） and 0th order will occur accordingly. This can consume redundant carrier and suppress the transient relaxation oscillation, which may be applied in some areas like on-off switching modulation of DFB semiconductor lasers. As an example, an equivalent n phase shift （n-EPS） is carefully designed to realize the effect. In such a laser the 0th order wavelength is in the margin of the material gain region and the -1st order wavelength is around the gain peak, while the stable single longitudinal mode （SLM） operation of the -lst order is guaranteed. The simulation investigation is performed. Good results with suppressed relaxation oscillation and 1.25 Gb/s directly on-off modulation （32 dB extinction ratio） are demonstrated. We believe it provides a new kind of method for on-off switching with high extinction ratio and weak relaxation oscillation.

取样结构λ/8 DFB半导体激光器特性研究

研究了基于取样光栅结构的λ/8相移DFB半导体激光器的调制特性。实验结果表明,λ/8 DFB半导体激光器单模特性良好,边模抑制比在45d B以上。在70m A的注入电流情况下,激光器的调制带宽达到16GHz,其无杂散动态范围也达到87d B/Hz2/3。

全息曝光实现的20波长DFB半导体激光器阵列

报道了一种基于全息曝光技术实现的20波长分布反馈式(DFB)半导体激光器阵列。传统的DFB半导体激光器光栅一般是利用电子束曝光的方式来实现,这种方式精度较高,然而成本昂贵并且非常耗时,不适合大规模生产应用,而全息方式制作容易,成本很低,适合大规模生产应用。实验结果表明,利用全息曝光技术实现的DFB激光器阵列具有良好的光电特性,激光器阵列的波长偏差在-0.5 nm至0.45 nm,阈值电流在13m A至17 m A,斜效率为0.4 W/A;50 m A偏置电流下,边模抑制比都大于40 d B。

取样光栅分布反馈激光器阵列器件研究

采用了一种基于取样光栅原理制作多通道增益-折射率耦合型光栅的方法,成功制作了8波长分布反馈(DFB)激光器阵列,阵列中各激光器的阈值电流为30～40 mA,注入电流为100 mA时的平均输出光功率为10mW,阵列器件实现了波长的可选择性激射,相邻激光器间的频率间距为200 GHz,验证了用取样光栅方法制作DFB激光器阵列的可行性。