光子晶体微腔半导体激光器的研究进展

概述了光子晶体微腔半导体激光器的研究进展，从物理机理、数值模拟、以及工艺实现方法等方面作了详细的叙述，并对其在光子集成中的应用前景进行了展望。     

Enlarged Photonic Band Gap in Heterostructure of Metallic Photonic and Superconducting Photonic Crystals

We show theoretically that the frequency range of photonic band gap of a hetero-structure which is made of a metallic photonic and superconducting photonic crystal can be enlarged due to the combination of the reflection band properties of the superconductor–dielectric (PC1) and metallic–dielectric (PC2) periodic structures. The transmittance and band structure of the considered structures are calculated using simple transfer matrix method and the Bloch theorem. Beside this, we have also calculated the transmittance of the superconducting photonic structure (PC1), metallic photonic structure (PC2) and heterostructure of metallic photonic and superconductor photonic crystals (PC1/PC2) for TE and TM-mode at the different angles of incidence.     

波导光子晶体的态密度

令方形波导内的电介质介电常数沿波导方向周期变化,实际上是非周期方向受限的一维光子晶体,不妨称为波导光子晶体。本文利用经典电动力学的方法计算了波导光子晶体的态密度,发现当波导宽度与其内部一维光子晶体晶的格常数可比拟时,会出现光子带隙;而且,波导宽度对系统的态密度有明显影响,随着波导宽度的增大光子带隙逐渐闭合。     

Superconducting Point Defect in a Two-Dimensional Photonic Crystal

This paper presents the tunability of the high temperature superconducting (SC) point defect modes in a two-dimensional photonic crystal composed of circular cylinders on a square lattice. By some modifications on the plane wave expansion method, we have shown that the properties of the SC point defect modes strongly depend on the temperature and external magnetic fields. The superconductor type and the nearest-neighbor of the defect effects are further investigated. Comparison between SC and conventional defects show that the SC one has only a monopole profile for different values of the defect size, and has very low sensitivity on the disorders, which is an important feature from a manufacturing point of view.     

Angle- and Thickness-Dependent Photonic Band Structure in?a?Superconducting Photonic Crystal

The angle- and thickness-dependent photonic band structures in a one-dimensional superconducting photonic crystal are theoretically investigated based on the transfer matrix method. The band structure is studied near and below the threshold frequency at which the superconducting material has a zero permittivity. The gap structure is analyzed as a function of the thicknesses of the two constituent superconducting and dielectric materials. In the angular dependence of the band structure, it is found that in the TM-polarization there exists a strongly localized superpolariton gap in the vicinity of the threshold frequency. This gap is shown to be enhanced as the angle increases.     

Study of Superconducting State Parameters of Binary Metallic Glasses by Pseudopotential Method

The theoretical calculation of the superconducting state properties (SSP) viz electron–phonon coupling strength λ, Coulomb pseudopotential μ ^*, transition temperature T _C , isotope effect exponent α and effective interaction strength N _O V of 50 binary metallic glasses of simple, non-simple, and transition metals have been carried out using a well-recognized model potential. We have employed here five different types of local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru–Utsumi (IU), Farid et al. (F), and Sarkar et al. (S) to study the exchange and correlation effects on the present investigations. Instead of using Vegard’s law, a pseudo-alloy-atom model (PAA) in the present investigation is proposed and found successful. The present results of the SSP are found to be in qualitative agreement with other such earlier reported data wherever they exist, which confirms the superconducting phase in the metallic glasses.     

Photonic crystal-based RGB primary colour optical filter

Abstract

We have presented an RGB optical filter, based on photonic crystal (PhC) waveguides, with the hexagonal arrangement of GaP rods in air. It filters out the three primary colours of the visible range, red (R, λ = 648 nm), green (G, λ = 540 nm) and blue (B, λ = 470 nm). The plane wave expansion method is applied for estimating the dispersion curves and finite element method is utilized in examining the propagation characteristics of the designed PhC-based optical filter. Transmittance, extinction ratio and tolerance analysis have further been calculated to confirm the performance of the proposed optical filter to work in the visible range of optical spectrum and filter out the three primary colours (red, green, blue) along different output ports.     

Silicon Photovoltaics Using Conducting Photonic Crystal Back‐Reflectors

Currently, research is being directed towards thinning conventional 200–300µm thick silicon photovoltaic cells by an order of magnitude or more. The benefits of reducing the cell thickness include decreased material costs, enhanced cell flexibility, and reduced effects of light‐induced degradation. However, one of the major challenges associated with reducing the active region to this extent is the corresponding reduction of light absorption. To mitigate this effect it has been proposed that the cell should incorporate enhanced light‐trapping strategies. One potential approach to enhance light trapping in thin photovoltaic cells is to structure the back‐reflector in the form of a photonic crystal (PC). It has recently been shown that two fundamental attributes of PC back‐reflectors optically coupled to thin semiconductor films contribute to enhanced absorption in the semiconductor: (i) the PC back‐reflector behaves as a perfect mirror, exhibiting complete reflection over stop‐gap frequencies; and (ii) the PC–semiconductor film interface couples incident light into resonant states that propagate along the plane of the film, thereby further enhancing the absorption. Although the ability of PC back‐reflectors to enhance absorption is encouraging, significant challenges arise when attempting to incorporate this light trapping technique in photovoltaic devices. Herein, we describe the underlying physical mechanisms that give rise to absorption enhancements in thin Si wafers featuring PC back‐reflectors, and describe hurdles that will have to be surmounted in order to reduce‐to‐practice a PC back‐reflector into an actual PV device.