纳米压印λ/4相移分布反馈激光器的单模稳定性

Lasing Mode Stability in Nano-Imprinted Quarter-Wavelength Phase-Shifted Distributed Feedback Laser Diodes

利用沿谐振腔体的一维数值模型着重研究了采用纳米压印技术制作的λ/4相移光栅分布反馈半导体激光器(QPS-DFB-LD)的光谱特性对谐振腔体参数的依赖性。通过将理论计算的结果与实测光谱对照,抽取了用于理论计算的QPS-DFB-LD模型参数。计算结果表明,相移区对中心位置的偏离量较小时(不超过10%)不会对器件的光谱特性造成很大影响,而仅仅是带来微小的蓝移和边模抑制比(SMSR)的变化。而当相移区对中心位置的偏离实际存在时,距离相移区较近的一端光输出功率增大而另一端光输出功率减小,并且距离相移区较近的一端输出光谱SMSR略高。器件两端蒸镀减反膜后所残留的反射率仍会使激射模在一定范围内产生漂移,并使其SMSR产生一定程度上的劣化。

Based on one-dimensional numerical model for resonant cavity, the dependence of laser spectrum on resonant cavity parameters in quarter-wavelength phase-shifted distributed feedback laser diodes （QPS-DFB-LD） is studied. Comparing theoretical calculation result with measured spectrum, the model parameters of QPS-DFB-LD used in theoretical calculation are given. Simulation results show that the minor deviation of QPS （〈 10% ） cannot affect laser spectrum greatly, but brings a minor blue shift and a slight change on the side-mode-suppression-ration （SMSR）. Once the deviation of QPS exists, higher output power will be obtained from the facet closer to QPS region while lower output power will be collected from the other facet. The side of output spectrum SMSR closer to QPS region will be slightly higher. Mter coating anti-reflective film, residue reflection index of both facets will introduce a drift to the laser mode wavelength within certain range, and will deteriorate the SMSR.