Wire‐grid polarizers in modern LCOS light‐engine configurations

Abstract— Wire‐grid polarizers that have a very high transmission, reflection, polarized‐light optical performance, and opto‐mechanical packaging advantages compared to the older polarization technologies have been developed. The wire‐grid polarizer operation principles and performance data are reviewed. The power of using finite‐difference time‐domain (FDTD) modeling techniques to understand the interaction of the electromagnetic waves with the wires and improve the optical performance of the wire‐grid polarizers and ultimately the light‐engine optical performance is shown. The ability to ray trace through a complete digital projector light engine from light source to the screen, including the wire‐grid polarizers, will be discussed. The main focus is to present the modern LCOS light‐engine architectures that use the wire‐grid polarizers. One‐, two‐, and three‐panel LCOS light engines are covered.     

Analysis for scattering of conductive objects covered with anisotropic magnetized plasma by trapezoidal recursive convolution finite‐difference time‐domain method

The finite‐difference time‐domain method (FDTD) is extended to three‐dimensional (3D) anisotropic magnetized plasma based on the trapezoidal recursive convolution (TRC) technology. The TRC technique requires single convolution integral in the formulation as in the recursive convolution (RC) method, while maintaining the accuracy comparable to the piecewise linear recursive convolution (PLRC) method with two convolution integrals. In this article, the numerical results indicate that the TRC‐FDTD method not only improves accuracy over the RC‐FDTD with the same computational efficiency but also spends less computational time than the PLRC‐FDTD based on the same accuracy. The 3D TRC‐FDTD formula is provided and the bistatic radar scattering sections of conductive targets covered with anisotropic magnetized plasma are calculated. The results show that magnetized plasma cover layer can greatly reduce echo energy of radar targets, and the anisotropic magnetized plasma cover has better absorption effect than nonmagnetized. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Analysis of multilayered homogeneous dielectric targets by using time‐domain physical optics method

An improved time‐domain physical optics (TDPO) method is proposed to simulate multilayered dielectric structures, in which the characteristic matrix theory of multilayered medium is implemented. In order to accurately calculate the total reflection coefficient on the surface of the multilayered medium, a series of two‐dimensional characteristic matrices are established. Based on the characteristic matrices, the total reflection coefficient can be directly derived, instead of summing up the multiple reflected and refracted waves, which is insensitive to the number of the number of the layers and the polarization of the incident wave. Numerical examples are given to validate effectiveness of the proposed TDPO method. It states that this method has much higher computational efficiency, without the loss of accuracy.     

Implementation of convolutional perfectly matched layer for three‐dimensional hybrid implicit‐explicit finite‐difference time‐domain method

The hybrid implicit‐explicit (HIE) finite‐difference time‐domain (FDTD) method with the convolutional perfectly matched layer (CPML) is extended to a full three‐dimensional scheme in this article. To demonstrate the application of the CPML better, the entire derivation process is presented, in which the fine scale structure is changed from y‐direction to z‐direction of the propagation innovatively. The numerical examples are adopted to verify the efficiency and accuracy of the proposed method. Numerical results show that the HIE‐FDTD with CPML truncation has the similar relative reflection error with the FDTD with CPML method, but it is much better than the methods with Mur absorbing boundary. Although Courant‐Friedrich‐Levy number climbs to 8, the maximum relative error of the proposed HIE‐CPML remains more below than ?71 dB, and CPU time is nearly 72.1% less than the FDTD‐CPML. As an example, a low‐pass filter is simulated by using the FDTD‐CPML and HIE‐CPML methods. The curves obtained are highly fitted between two methods; the maximum errors are lower than ?79 dB. Furthermore, the CPU time saved much more, accounting for only 26.8% of the FDTD‐CPML method while the same example simulated.     

Parameter extraction of interdigital slow‐wave coplanar waveguide circuits using finite difference frequency domain algorithm

The slow wave effect can be obtained by a capacitively loaded structure with a symmetrical interdigital line connected on both sides of the coplanar waveguide (CPW) central line. The ferroelectric thin film with high dielectric constant can reduce the size of circuit and make it possible to realize tunable devices such as filter by applying voltage on it. Actually, this kind of slow wave structure is a periodic guided‐wave structure and can be analyzed by using classic finite difference frequency domain (FDFD) method for periodic guided‐wave structures. However, the very compact slow‐wave structures will usually result in simulation errors when the classic FDFD method is adopted, which will lead to a nonsymmetrical generalized eigenvalue problem. In this article, the shift‐and‐invert (SI) Arnoldi method is used to directly resolve this nonsymmetrical generalized eigenvalue problem. As a result, the accuracy of FDFD algorithm is improved. Especially for the large scale eigenvalue problem, SI method can also have a very fast speed of calculation. By means of its complex propagation constant obtained from simulation, one can extract circuit parameters of the interdigital capacitor. Consequently, one can analyze and design relevant resonators and filters in a quick and accurate manner, which are constructed with such interdigital slow wave structures. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.