Research On Slow Light Effect And Light Transmission Properties Of Photonic Crystals

Slow light promotes stronger light-matter interaction, it provides additional control over the spectral bandwidth of this interaction and it allows us to delay and temporarily store light in all-optical memeories. So it is of great importance to study the slow light technology. Traditional laboratory conditions to achieve the desired slow light are very strict so that it is difficult to let the slow light be applied to the actual project. The experiment to achieve slow light in photonic crystals can be carried out under normal laboratory environment without any special external conditions. The enhancement of the interaction duration of the optical pulse is strongly associated with the amount of reduction in group velocity. Since PCs have highly dispersive structures, that property can be tailored for the purpose of slow wave by either altering the parameters of the structure or building special structure. This article is based on the change of structure,the main contents are as follows:The background and significance of research on photonic crystals and slow light technology are explained. Situation and development of related technologies and issues to be addressed are summarized. Then, the electromagnetic characteristics and effects of slow light photonic crystals were analyzed by graphic illustration about the principles that how slow light was generated. And the existing research methods that is related to this article are elaborated.We proposed a new surface slow light PC structure based on surface Bloch modes.Then, the dispersion relation of the photonic structure is obtained by the PWE method.The straightforward manipulation of the dispersion bands revealed the slow light property of the surface defect PC structure. The slow light property, along with low GVD, is assured by designing flat bands. The findings of the frequency domain analysis are verified by the time-domain simulation software COMSOL. Effective slow light phenomenon is obtained through the finite element method.Two line-defect structures are presented for the line-defect waveguide, one is based on reducing the middle row of media column radius and the other is the removement of the middle row part of media column. The plane wave expansion method is firstly used.By changing the radius of the dielectric column, we know that the maximum photonic band gap of the periodic structure can be obtained when its radius of the square latticephotonic crystal is 0.20 a. Then the numerical analysis about the optical transmission in both square lattice photonic crystal line defect waveguide is executed, by changing the medium column radius in the waveguide and going on simulation analysis, the best structure of the waveguide can be selected. Light transmission characteristics in frequency and time domains of the two structures can be received by finite element method in the COMSOL simulation. Transmission group speed of the plane waveguide in the first structure is 0.25 c and 0.172 c is the result in the second structure, which is consistent with the theoretical calculation by plane wave expansion method.