Subwavelength grating waveguide filter based on cladding modulation with phase-change material grating

TL;DR

This paper introduces a silicon subwavelength grating waveguide filter utilizing phase-change material GST, enabling reconfigurable optical filtering with high extinction ratio and tunability through phase transitions.

Contribution

It demonstrates a novel integrated filter design that combines subwavelength engineering with phase-change materials for reconfigurable photonic functionalities.

Findings

Achieved an extinction ratio of 28.8 dB in the filter.

Demonstrated a tunable blueshift of over 4 nm via partial crystallization of GST.

Studied the effects of GST geometry and placement on filter performance.

Abstract

Subwavelength engineering and utilizing phase-change materials with large contrast in their optical properties have become powerful design tools for integrated silicon photonics. Reversible phase-transition of phase-change materials such as Ge2Sb2Te5 (GST) provides a new degree of freedom and opens up the possibility of adding new functionalities to the designed devices. We present an optical filter based on a silicon subwavelength grating (SWG) waveguide evanescently coupled to phase-change material loading segments arranged periodically around the SWG core. The effect of the GST loading segments' geometry and their distance from the SWG core on the filter's central wavelength and bandwidth are studied with three-dimensional finite-difference time-domain simulations. The employment of GST in the structure adds a switching functionality with an extinction ratio of 28.8 dB. We also examine the possibility of using the proposed structure as a reconfigurable filter by controlling the partial crystallization of the GST offering a blueshift of more than 4 nm.