Properties of single and multiple defect modes in one-dimensional photonic crystals containing left-handed metamaterials

Wave propagation is studied in structures consisting of alternate left- and right-handed layers. Bragg gap and zero-n gap appear in different frequency regions of the structure. The periodicity of the structure is broken by simply reversing the order of the layers in one half of the structure, resulting in defect modes located inside the zero-n gap and Bragg gap. These modes can be made very narrow by adding more layers in the structure. The defect mode located inside the zero-n gap is sensitive to the symmetry of the structure and insensitive to the angle of incidence of the incoming radiation. Multiple modes are also generated inside the gaps by repeating the structural pattern. Thus, a simple structure can be used for single and multiple modes that are imDortant for different applications.

Modelling Upgrading Maintenance Policy in the One-Dimensional Renewing Warranty Period

In the one-dimensional renewing warranty period,the quality of the spares for product is likely to be improved during the warranty period.Therefore,upgrading maintenance becomes more and more common.Then the manufacturers(customers) may have to decide whether or not to provide(buy) the warranty considering upgrading maintenance.This paper presents a mathematical model considering upgrading maintenance for products with multiple failure modes.Upgrading maintenance is taken into account with the assumption that the warranted item is upgraded one time during the warranty cycle.The upgrading maintenance is carried out,when the corrective maintenance is taken place.After upgrading maintenance,the high-quality spares are used to replace the failed item.In the numerical example,the results of the models are calculated.Monte Carlo simulation results are compared with the analytical results to demonstrate the correctness and efficiency of the proposed models considering upgrading maintenance.

Omni-directional mirror for visible light based on one-dimensional photonic crystal

The omni-directional reflection characteristics of one-dimensional photonic crystals composed of Ta2O5/MgF2 multi-quantum well （MQW） are studied using the transfer matrix method. An omnidirectional reflector consisting of three and four Ta2O5/MgF2 MQWs is investigated. Results show that the photonic band gap of the photonic crystal composed of three and four Ta2O5/MgF2 MQWs, which are within the wavelength ranges of 402-712 and 412-1,023 nm, respectively, could cover the entire visible region. The relationship among the width of the band gap, its location, reflectivity rate, and incident angle of the incident light is analyzed. The optimal structural parameters of the MQW of the omni-directional reflector in the visible region are also calculated. The calculations provide a guide for the design of omni- directional reflection devices in the visible region.