In the conventional method for design of waveguide filters, equivalent circuits such as impedance or admittance inverters are used to model the waveguide discontinuities. These inverters are useful for design of filters with narrow bandwidth. In this paper using a genet More
In the conventional method for design of waveguide filters, equivalent circuits such as impedance or admittance inverters are used to model the waveguide discontinuities. These inverters are useful for design of filters with narrow bandwidth. In this paper using a genetic algorithm and mode-matching (MM) method, and without using the equivalent circuits, two E-plane and H-plane bandpass waveguide filters are designed. To verify the validity of MM method, the frequency response of filters is obtained by the PML-FDTD method. The two filters are also analyzed by the HFSS software. The results of MM method are in excellent agreement with the results provided by FDTD method and HFSS software. An important characteristic of a waveguide filter is the sensitivity of its frequency response to fabrication errors. In this paper, by using the Monte Carlo statistical method, sensitivity of the frequency response of E-plane and H-plane filters to fabrication errors are determined and compared with each other.
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The iterative angular spectrum (IAS) method has been introduced by Mellin and Nordin for designing finite-aperture diffractive optical elements (FADOEs). We have extended this method to two-dimensional FADOEs and used it to design some optical devices. The first device More
The iterative angular spectrum (IAS) method has been introduced by Mellin and Nordin for designing finite-aperture diffractive optical elements (FADOEs). We have extended this method to two-dimensional FADOEs and used it to design some optical devices. The first device is a 1-to-7 beamsplitter that couples an optical beam to seven single-mode optical fibers with a diffraction efficiency of 84%. The second device is a beam-shaper that converts a Gaussian beam into a nearly flat beam with a diffraction efficiency of 74.8%. The third design is a 1-to-3 asymmetric beamsplitter. The fourth design includes three microlenses with different focal lengths. The desired intensity distribution patterns of all these designs are located at the near field region. We have investigated the sensitivity of the extended method by comparing the results obtained by this method with those obtained by three-dimensional finite difference time domain (3-D FDTD) method using perfect matched layer (PML). Also, a 1-to-5 beamsplitter is fabricated and the experimental results are presented.
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