Modulation of Q Factor and Fano Lineshape in Ge2Sb2Te5-Based Grating Structure

In this paper, the modulation of the Fano resonance (FR) of dielectric grating has been demonstrated by controlling the crystallization fraction of phase change material film. We analyze the optical characteristics of the grating structure thoroughly by the energy band structure, Q factor, and the electric field distribution of three TE modes. It is verified that the Q factor and the Fano lineshape are related to the thickness of the Ge₂Sb₂Te₅ (GST) layer. In addition, by changing the crystallization fraction of the GST layer, non-volatile modulation of the Q factor can be achieved. We also demonstrate that the crystallization fraction of the GST layer affects the Fano lineshape significantly. By changing the crystallization fraction of the GST layer, the non-volatile modulation of Fano lineshape from asymmetric parameter q = −1 to q = 1 can be achieved. These features make this grating structure an excellent optically reconfigurable device in various fields including lasing spaser and biosensing with improved performance.