Research On Optical Transmission In One-dimensional Disordered Photonic Crystals

Disorder effect inevitably exists in photonic crystals during the fabrication process.On the one hand,the undesirable scattering caused by imperfections effect is generally believed to impose a negative impact on the targeted properties of photonic devices.On the other hands,disordered photonic crystals not only play an important role in the life activities of animals and plants in nature,but also have widely prospect in the fields such as photonic devices,random lasers and solar cells.Therefore,uncovering how disorder affects light propagation in photonic crystals is of great significance both in theory and in applications.With the characteristics of simple structure and easy preparation,one-dimensional photonic crystals are widely used in various optical devices and optical researches.In this thesis,the influence of disorder effect on light propagation in one-dimensional photonic crystals is systematically studied on the view point of concentration of electric field energy.The main contents are as follows:1.An ideal one-dimensional photonic crystal model is established and then the intrinsic electric fields of the band edge modes in the region of its nine lowest order photonic band gaps are used to calculate the concentration factors.It is shown that low-frequency mode near the photonic band gap tends to concentrate its electric energy in the high-? region while high-frequency mode above the photonic band gap has a large fraction of its electric energy in the low-? region.2.Three types of one-dimensional photonic crystal models with disorder effect in refractive index are established.The transmission matrix method is used to calculate the transmission in the region of the nine lowest order band gaps.It is found that when weak disorder is introduced in the low-? layer,the low-frequency mode is robust to the disorder effect,while the high-frequency mode is sensitive to the disorder effect.When weak disorder is introduced into the high-? layer,the opposite result can be obtained.In addition to two types of trivial disorder-induced propagation scenarios,two nontrivial disorder-induced transportation scenarios are found near the photonic band edges: the first one is shown to be robust to weak disorder effect and the other one shows an abnormal conversion from the disorder-induced attenuation to an unexpected enhancement of transmission when the disorder strength surpasses a certain level.3.Two parameters are proposed to visualize how disorder effect can be used to manipulate the electric filed energy and light propagation in the photonic crystals.They can also be used as effective parameters for the identification of transitions between localization and delocalization.