Guided-mode resonant grating filter with an antireflective surface for the multiple channels

In this paper, a new type of guided-mode resonant grating (GMRG) filter with an antireflective surface called the 'moth-eye structure' for the multiple channels is presented by using rigorous coupled-wave analysis (RCWA) and the S-matrix method. Long range, low sidebands and multiple channels are found when the GMRG filters with antireflective surface are illuminated with incident polarization light. It is calculated that the multiple channel phenomenon can be shown when the depth of antireflective surface is increased. Moreover, the wavelengths of the multiple channels can be easily shifted by changing the depth of the homogenous layer which is under the antireflective surface, and the optical properties of GMRG filters such as low sideband reflection and narrow band are not badly spoiled when the depth is changed.

Nonpolarizing guided-mode resonance filter

A normal-incidence nonpolarizing guided-mode resonance filter is designed. There are two waveguide layers and one grating layer in the filter. By adjusting the distance between the two waveguide layers, the same resonance wavelength for both TE and TM polarization can be achieved. An antireflection design method is also used to decrease the sideband reflection of the filter. The results show that the filter has high reflection, more than 99.9% at 500 nm, and the FW-HMs of TE- and TM-polarized light are 2.16 and 0.15 nm, respectively. (C) 2009 Optical Society of America

Investigation on thermal stability of TiO2 films for application at high temperature

The thermal stability of electron beam deposited TiO2 monolayers and TiO2/SiO2 high reflectors (HR) during 300 to 1100 degrees C annealing is studied. It is found that the optical loss of film increases with the increase in annealing temperature, due to the phase change, crystallisation and deoxidising of film. Scattering loss dominates the optical property degradation of film below 900 degrees C, while the absorption is another factor at 1100 degrees C. The increase in refractive index and decrease in physical thickness of TiO2 layer shift the spectra of HR above 900 degrees C. The possible crack mechanism on the surface of HR during annealing is discussed. Guidance for application on high temperature stable optical coatings is given.

Convergence Properties and Fixed Points of Two General Iterative Schemes with Composed Maps in Banach Spaces with Applications to Guaranteed Global Stability

This paper investigates the boundedness and convergence properties of two general iterative processes which involve sequences of self-mappings on either complete metric or Banach spaces. The sequences of self-mappings considered in the first iterative scheme are constructed by linear combinations of a set of self-mappings, each of them being a weighted version of a certain primary self-mapping on the same space. The sequences of self-mappings of the second iterative scheme are powers of an iteration-dependent scaled version of the primary self-mapping. Some applications are also given to the important problem of global stability of a class of extended nonlinear polytopic-type parameterizations of certain dynamic systems.

Stability analysis and observer design for discrete-time SEIR epidemic models

This paper applies Micken's discretization method to obtain a discrete-time SEIR epidemic model. The positivity of the model along with the existence and stability of equilibrium points is discussed for the discrete-time case. Afterwards, the design of a state observer for this discrete-time SEIR epidemic model is tackled. The analysis of the model along with the observer design is faced in an implicit way instead of obtaining first an explicit formulation of the system which is the novelty of the presented approach. Moreover, some sufficient conditions to ensure the asymptotic stability of the observer are provided in terms of a matrix inequality that can be cast in the form of a LMI. The feasibility of the matrix inequality is proved, while some simulation examples show the operation and usefulness of the observer.