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Feasibility study of a Ge₂Sb₂Te₅-clad silicon waveguide as a non-volatile optical on-off switch

Song, J., Ghosh, S. ORCID: 0000-0002-1992-2289, Dhingra, N. , Zhang, H., Zhou, L. & Rahman, B. M. ORCID: 0000-0001-6384-0961 (2019). Feasibility study of a Ge₂Sb₂Te₅-clad silicon waveguide as a non-volatile optical on-off switch. OSA Continuum, 2(1), pp. 49-63. doi: 10.1364/OSAC.2.000049


This paper reports on the design optimization of compact optical ON-OFF switches based on a GST-clad silicon rib waveguide and compares it to a GST-clad silicon nanowire at the telecommunication wavelength 1.55 µm. Effective index and modal loss of the quasi-TE modes are calculated by a full-vectorial H-field finite element method. It shows that the electro-refraction effect-based switch may not be viable because of the higher modal loss in the GST crystalline state. On the other hand, the larger modal loss difference between GST amorphous and crystalline states would be more suitable for an electro-absorption type switch design. The effect of silicon slab thickness, silicon core width, and GST layer thickness for both the waveguides are presented. As the presence of the GST layer modifies the mode field profiles, so the incurring coupling loss at the butt-coupled junctions between the input/output silicon waveguide and Si-GST waveguide are also calculated by using the least squares boundary residual method. These results show that the GST-clad silicon rib waveguide with a 500-nm-wide silicon core, 60-90 nm thick silicon slab, and 15-25 nm thick GST layer is the optimal self-sustained switch design. In this case, a very compact, 2-5 µm long device is expected to show an extinction ratio of more than 20 dB with the total insertion loss of only 0.36 dB.

Publication Type: Article
Additional Information: © 2019, Optical Society of America
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments: School of Science & Technology > Engineering > Electrical & Electronic Engineering
Text - Accepted Version
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