Silicon Add-Drop Multiplexer Based on π Phase-Shifted Antisymmetric Bragg Grating

Abstract

We proposed a new kind of add-drop multiplexer based on π phase-shifted antisymmetric Bragg grating ( π-ASBG). Light resonance is formed in the π-ASBG with mode conversion between backward fundamental transverse electric (TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) mode and the forward first order transverse electric (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) mode. With the aid of the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> mode generated in the π -ASBG, add-drop multiplexer can be designed. As examples, two multiplexer structures based on single- and dual-bus resonator, on silicon-on-insulator (SOI) platform have been studied in detail. Besides, no light is reflected to the input port, if the structure is carefully designed with critical coupling condition satisfied. For the fabricated add-drop multiplexer based on single-bus resonator, the extinction ratio is 23.90 dB and full width at half maximum (FWHM) is 0.33 nm at the through port. For the fabricated add-drop multiplexer based on dual-bus resonator, the extinction ratio is 17.22 dB and FWHM is 0.29 nm at through port. The results show that proposed structures provide a new method to realize add-drop multiplexer and other integrated optical filters for optical communications and sensors.