含正负介质光子晶体在角度入射情况下的带隙结构变化

Change of band gap structure of 1-D photonic crystal of periodic positive-negative index structure at angular incidence

采用传输矩阵法研究了在角度入射情况下由PIM/NIM组成的一维光子晶体的透射谱,得到其带隙结构的变化规律:光子晶体的带隙结构会随着入射角的改变而改变,尤其对于色散的NIM与PIM组成的一维光子晶体,在n_N≈0附近会产生一个新的带隙,新带隙的中心位置保持不变,但宽度会随着入射角的增大而变宽;第一级Bragg隙的中心位置和隙宽也随着入射角的变化而变化,这为二次谐波效应实现完全相位匹配创造了条件。

The transmission spectra of 1-D photonic crystal of periodic positive-negative index structure at angular incidence was studied by transfer matrix method. The results show that the photonic band gap structure changes along with the change of incidence angle, especially for the dispersive 1-D photonic crystal composed of positve and negative refractive index materials, a new type of photonic band gap corresponding to zero of negative refractive index arises, of which the center is invariant upon the change of incidence angle, but the width broadens when the incidence angle increase; likewise, for a Bragg gap, the center and width of band gap change, which make the condition of achieving complete phase matching for the second harmonic effect.