Refractive Index Of Defect Layer Research Articles

A defective one-dimensional superconducting photonic crystal design for the generation of the Fano resonance feature

In the present work, we demonstrate the generation of Fano resonance (F) feature based on a defected one dimensional superconducting photonic crystal design. Our proposed design consists of alternated layers of high-temperature superconductor material with conventional ones. By using the transfer matrix method, we investigate the optical properties for the proposed designs. The obtained optical properties show two sharp peaks with zero side band of reflectivity are resulted NIR region. Then, by adding a defect layer to the periodic structure, we find that two peaks are appeared in the obtained spectrum which they are indicated for electromagnetic induced reflection (EIR) and Fano resonance concept. Finally, by adjusting the design parameters of our proposed structure such as the number of periods, the thickness of the constituent layers, and the refractive index of defect layer, we investigated the corresponding optical properties response. Our proposed designs can be used in some potential applications such as in the optical devices as switching, slow-light and sensor.

Induced reflection in Tamm plasmon systems.

We present an induced reflection response analogue to electromagnetically induced transparency (EIT) in a novel Tamm plasmon system, consisting of a thin metal film and a Bragg grating with a defect layer. The results show that an induced narrow peak can be generated in the original broad reflection dip, which is attributed to the coupling and interference between the Tamm plasmon and defect modes in the grating structure. It is found that the EIT-like induced reflection is strongly dependent on the thickness of defect layer, grating period number between the metal and defect layers, thickness of Bragg grating layer, refractive index of defect layer, and thickness of metal film. Additionally, the induced reflection can be dynamically tuned by adjusting the angle of incident light. The numerical simulations agree extremely well with theoretical calculations. The coupling strength between the Tamm plasmon and defect modes is determined by the above parameters. These results will provide a new avenue for light field control and devices in multilayer photonic systems.

Narrow transmission band of one-dimensional photonic crystals with a defect layer

Photonic crystals (PCs) containing defects have important applications in optical filtering with super narrow transmission band and photo phase adjustment. Resonance transmission bands in one-dimensional PCs with a defect mode are calculated by the transfer matrix method. The effect of two primitive dielectric refractive index ratios and position of the defect in PCs on filter quality are analyzed. The photonic band gap of PCs, the narrow resonance transmission band made by defect, and the relationship between refractive index of defect layer and the peak value of narrow resonance transmission band are discussed. The physical mechanisms can be explained by the photonic potential well and potential barrier scattering for photons.

Finite-difference time-domain analysis of optical bistability with low threshold in one-dimensional nonlinear photonic crystal with Kerr medium

We present a nonlinear finite-difference time-domain (NFDTD) analysis of optical bistability (OB) in a one-dimensional nonlinear photonic crystal (1D-NPC) with Kerr medium under Debye relaxation. The properties of the defect modes in a symmetrical structure 1D-NPC and the way to obtain low threshold of OB is discussed in detail. The OB threshold depends on the optical thickness and refractive index of defect layer and the number of symmetrical layers. When the half-width of defect mode is small enough and frequency of incident light and linear refractive index are selected carefully, the low threshold OB is able to be obtained. By numerical simulation threshold ∼ 130 KW/ m 2 is obtained, correspond refractive index change is only about 0.04.

Photonic defect modes of cholesteric liquid crystals.

We investigate defect modes of cholesteric liquid crystals as photonic band gap materials. For normal incidence of light, cholesteric liquid crystals exhibit total reflection for the circular polarization with the same handedness as that of cholesteric helix. However, the other orthogonal component is completely transmitted. When we replace a thin layer of liquid crystal by an isotropic material as a defect, defect modes are induced for both polarizations of incident light. We analyze the wavelength and reflectivity of the defect modes in terms of the refractive index of defect layer.