In this study, we focus on the analysis of one-dimensional photonic crystal with symmetric double defect. Using the transfer matrix method (TMM), the properties of defect modes including degeneracy and splitting, can be analyzed in detail. It is found that such properties are mainly depending on symmetry and spatial interval of defects. The results show that the degeneracy of defect modes occurs in two defects separate to each other. And defect modes split when two defects close to each other. The results have potential applications in photonic integration and fiber optic sensor.
Using 4×4 transfer matrix method, we investigated the transmission properties of defect mode in one-dimensional photonic crystal. The system can be transformed to be biaxial photonic crystal under one-way stress. It is found that the transmission properties of defect mode are critically depending on the numbers of dielectric layers and degree of asymmetry. For the system without stress, in the case of system with mirror symmetry, the defect mode is appearing gradually and its peak wavelength always keeps stable with the numbers of dielectric layers increasing, and its corresponding transmittance will be sharply decrease from a constant to zero at the same time. In the case of asymmetry, the defect mode is appearing gradually and its peak wavelength still keeps stable with the asymmetric degree continuously growth. Meanwhile, its transmittance exist an evolution from increase to decrease in this progress, and the maximum transmittance can be obtained at Δm=0 . After applying a fixed one-way stress on the system, the single defect mode will be split into Left-side defect mode (LDM) and Right-side defect mode (RDM). In the case of system with mirror symmetry, the two defect modes are appearing gradually and their peak wavelength always keep constant with the numbers of dielectric layers increasing, respectively, and their corresponding transmittance decrease asynchronously from a constant to zero. In the case of asymmetry, the peak wavelengths of LDM and RDM are being a constant with the changing of asymmetric degree and their corresponding transmittance are synchronously increasing or decreasing with the continuously increasing of asymmetric degree. Particularly, the maximum transmittance of defect mode also can be obtained at Δm=0 . This study provided a theoretical guidance for the best choice of numbers of dielectric layers to design a pressure sensor.
Based on a model of coupling Maxwell's equations with the rate equations of electronic population, the spatial-distribution
and spectrum-characteristics as well as amplified properties of defect modes such as lasing threshold,
saturated output in a single-defect active photonic crystal are investigated through finite-difference time-domain method.
Influences of the number of crystal periods and spatial profile on amplified feature are also analyzed. The results show
that the lasing threshold and saturated output depend directly on the number of crystal periods and the spatial profile of
defect modes; the defect mode with lower mode area has a low-threshold. Furthermore, the lasing threshold can be
further reduced as the saturated output increases if the number of crystal periods increase. Such a feature is important for
understanding of the interaction between optical gain and defect modes.
Using a time-independent calculation based on self-consistent transfer matrix method, we numerically investigate
localized mode in a one-dimensional (1D) weakly disordered medium containing Lorentz dispersive material. The result
show that the random medium containing dispersive media has frequency-dependent localized modes. Such localized
modes strongly depend on dispersive parameters, such as transverse optical phonon frequency ω0, oscillator strength Χ0 and thickness of dispersive layer. The resonant frequency of such mode can be modified to shift by applying a dispersive
medium. By this study, we will acquire some knowledge of localized mode in dispersive disorder medium; furthermore,
this study suggests a method to realize tenability of localized mode, which is important for application of random laser.