Novel Optical Filter Composed of Multiple-waveguide Directional Couplers

Novel Design of Optical Filters Based on a Pair of MMI Power Divider/Combiner

“…Owing to the increasing necessity of the filtering devices in optical communications, the authors have proposed several types of filters composed of multiple-waveguide directional couplers since 2001 [5][6][7]. Their geometrical layouts and patterns are similar to those used in the microwave engineering.…”

A Comparison of three Novel Optical Wavelength Filters with Cascaded Directional Couplers

“…Wavelength filters are important components in many conventional/modern optical apparatuses and optoelectronic integrated circuits, such as photonic devices used in wavelength-division-multiplexing (WDM) optical communication equipments and monochromatic optical information processing systems, Various designs for the fiber/waveguide filter structures were presented in literature [1][2][3][4][5]. Among them, the integrated-optical structure comprising multiple directional couplers in cascade, instead of coaxial fibers (or aligned waveguides) with different dimensions and refractive index profiles, could avoid serious insertion losses due to aberration and modal mismatching between the different sections of the filters.…”

“…Among them, the integrated-optical structure comprising multiple directional couplers in cascade, instead of coaxial fibers (or aligned waveguides) with different dimensions and refractive index profiles, could avoid serious insertion losses due to aberration and modal mismatching between the different sections of the filters. Moreover, the cascaded directional couplers just including parallel straight waveguides are more easily designed and fabricated with fewer defects in a single chip by the conventional photolithography process [5,6]. For these reasons, this type of optical wavelength filters is more promising.…”

“…For these reasons, this type of optical wavelength filters is more promising. However, for sake of obtaining narrow wavelength bandwidths, it usually needs many parallel waveguides such the filter structures composed of the cascaded directional couplers in [5] become laterally wide and occupy large area. In this work, we propose several new designs to reduce the widths and areas of the filtering devices.…”

“…In this work, we propose several new designs to reduce the widths and areas of the filtering devices. And the optical characteristics and performances of our proposed filters are analyzed and presented by the FDBPM with the Runge-Kutta algorithm (RKBPM) because RKBPM is an efficient and simple technique of designing optical waveguides [5][6][7][8][9].…”