Optical Switching Using Transition from Dipolar to Charge Transfer Plasmon Modes in Ge2Sb2Te5 Bridged Metallodielectric Dimers

• Published in: Scientific reports Vol. 7; no. 1; p. 42807
• Main Authors: Ahmadivand, Arash, Gerislioglu, Burak, Sinha, Raju, Karabiyik, Mustafa, Pala, Nezih
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.02.2017; Nature Publishing Group
• Subjects: 639/301/1019/1021; 639/624/400/1021; Crystallization; Electrical properties; External stimuli; Glass substrates; Humanities and Social Sciences; multidisciplinary; Nanoparticles; Nanowires; Numerical analysis; Optical properties; Random access memory; Science; Wavelengths
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep42807

Capacitive coupling and direct shuttling of charges in nanoscale plasmonic components across a dielectric spacer and through a conductive junction lead to excitation of significantly different dipolar and charge transfer plasmon (CTP) resonances, respectively. Here, we demonstrate the excitation of dipolar and CTP resonant modes in metallic nanodimers bridged by phase-change material (PCM) sections, material and electrical characteristics of which can be controlled by external stimuli. Ultrafast switching (in the range of a few nanoseconds) between amorphous and crystalline phases of the PCM section (here Ge 2 Sb 2 Te 5 (GST)) allows for designing a tunable plasmonic switch for optical communication applications with significant modulation depth (up to 88%). Judiciously selecting the geometrical parameters and taking advantage of the electrical properties of the amorphous phase of the GST section we adjusted the extinction peak of the dipolar mode at the telecommunication band (λ~1.55 μm), which is considered as the OFF state. Changing the GST phase to crystalline via optical heating allows for direct transfer of charges through the junction between nanodisks and formation of a distinct CTP peak at longer wavelengths (λ~1.85 μm) far from the telecommunication wavelength, which constitutes the ON state.