Designing an optical filter based on subwavelength grating slot waveguide embedded with phase-change material

چکیده مقاله

In the past decades, photonic integrated circuits have been considered to overcome the bandwidth limitations of electronics circuits. However, photonic devices have yet to offer the same reconfigurability and programmability available in their electronics counterpart. This challenge can be addressed by integrating phase-change materials such as Ge₂Sb₂Te₅ (GST) into photonic devices. We inserted a periodic arrangement of GST in a subwavelength grating (SWG) slot waveguide in order to have an optical filter with Bragg grating. The non-volatile and reversible phase-transition of GST, embedded in the silicon SWG slot waveguide, enables us to design a reconfigurable notch filter without static power consumption. The three-dimensional finite-difference time-domain (3D FDTD) simulation confirms that it is possible to create a 6.1 nm blueshift at the middle of the passband only by changing and controlling the phase transition of the GST. The spectral characteristics and their dependences on the geometrical parameters are investigated. The comparison of our filter with a conventional slot waveguide clearly indicates that the SWG slot waveguide provides a larger wavelength shift upon phase-transition of GST. Moreover, the SWG structure greatly improves the extinction ratio of the no