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Updated: Jul 16, 2026

Design and Characterization Methodology for Efficient Wide Range Tunable MEMS Filters
Published on: February 4, 2018
Finite-difference time-domain analysis of deformed square cavity filters with a traveling-wave-like filtering
Qin Chen1, Yue-De Yang, Yong-Zhen Huang
1State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing, China. chenqin@red.semi.ac.cn
Abstract:
An add-drop filter based on a perfect square resonator can realize a maximum of only 25% power dropping because the confined modes are standing-wave modes. By means of mode coupling between two modes with inverse symmetry properties, a traveling-wave-like filtering response is obtained in a two-dimensional single square cavity filter with cut or circular corners by finite-difference time-domain simulation. The optimized deformation parameters for an add-drop filter can be accurately predicted as the overlapping point of the two coupling modes in an isolated deformed square cavity. More than 80% power dropping can be obtained in a deformed square cavity filter with a side length of 3.01 microm. The free spectral region is decided by the mode spacing between modes, with the sum of the mode indices differing by 1.
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