一维光子晶体缺陷模激光器的放大特性

光子晶体中引入缺陷后将形成缺陷模,这些缺陷模在增益介质中将被放大形成激光。基于麦克斯韦方程和速率方程相结合的模型,用时域有限差分法(FDTD)计算和分析了一维单缺陷光子晶体激光器中缺陷模的空间分布和频谱特性,以及这些缺陷模的放大特性,主要研究了缺陷层的厚度、晶体层数对缺陷模放大特性的影响。模拟结果显示,类似于传统激光腔的腔模,这些缺陷模能够被放大,形成激光。调整缺陷层的厚度、晶体层数等结构参量,将改变缺陷模的谐振,激射频率以及空间分布,这将直接影响激射阈值和饱和特性。增加晶体的层数,激光器的阈值将降低,饱和值将增加,但晶体层数增加到一定限度时,这种增减趋势变弱。模拟结果证明了有效层数的存在。

Amplification of One-Dimensional Photonic Crystals Defect-Mode Laser

Defect modes will emerge in the emission spectrum as a defect is introduced in a photonic crystal,and such modes can be amplified to produce laser radiations.Based on the model that couples Maxwell's equations with the rate equations of electronic population,the spatial distribution and spectrum characteristics of the laser modes in a single-defect active photonic crystal are investigated by the finite-difference time-domain method, as well as the amplification of defect modes.The influences of the number of crystal periods and the thickness of the defect layer on amplification of defect modes are analyzed.The results show that the spectral property,resonance and radiation frequency,and spatial profile of defect mode depend directly on the medium parameters such as the number of crystal periods and the thickness of defect layer,which further influences the radiation threshold and saturation.The radiation threshold decreases and the saturated output increases when the number of crystal periods increases.Such a trend becomes weak when the number of the crystal periods is large enough and thus there exists an effective number for the crystal periods in the system.