光子晶体中掺杂激活杂质的光增益研究

Study on the Optical Gain of Photonic Crystals with Active Impurity

本文借助光子晶体中二能级原子的自发辐射理论说明缺陷态局域场存在的必然性以及局域场基本性质,为研究掺杂自发辐射的内在规律提供了理论依据,在此基础上,将自发辐射理论与数值模拟相结合,在缺陷介质中掺入和未掺入激活杂质时,数值模拟研究一维光子晶体的掺杂局域场特征以及受激辐射增强和透射率大于1现象与光子带隙边缘群速度异常和掺杂层复有效折射率负的虚部之间的内在规律,由此说明如在光子晶体的缺陷介质中掺入激活杂质,复有效折射率具有负的虚部,光子禁带中会出现品质因子非常高的杂质态,具有很大的态密度,这样便可实现自发辐射的增强,出现较强的受激辐射放大,在带隙的边缘处,光子晶体的群速度较小或群速度异常,受激辐射放大最容易出现在靠近光子带隙的边缘。

We have proved the inevitability of the existence of localized field with a defect mode as well as its basic properties with the help of the theory of spontaneous emission from two-level atoms in photonic crystals, which provide a theoretical proof for studying the inherent laws of spontaneous radiation from the doped medium in the paper. On this basis, the inherent laws between the characteristics of localized field, the enhancement of stimulated emission, the phenomenon of transmissivity greater than 1, the abnormality of the group velocity close to the edge of photonic band gap and the negative imaginary component of the complex active refractive index of doped layers in one-dimensional photonic crystals with active impurities or without active impurities were studied by using the method of numerical simulation, which illustrated that the complex active refractive index has a negative imaginary component, and that the dope modes with very high quality factors and great mode density will occur in the photonic forbidden band if an active impurity is introduced into the defect medium in the photonic crystals. Therefore, the enhancement of spontaneous emission can be realized, and the amplification of stimulated emission will be very great and it most probably occurs close to the edge of photonic band gap with the fundamental reason and the group velocity close to the edge of band gap being very small or abnormal.