Tapered waveguide mode converters for metal-insulator-metal waveguide plasmonic sensors

• Published in: Measurement : journal of the International Measurement Confederation 2023-04, Vol.211, p.112601, Article 112601
• Main Authors: Butt, M.A., Kazanskiy, N.L., Khonina, S.N.
• Format: Article
• Language: English
• Subjects: Dielectric to plasmonic mode converter; Metal-insulator-metal waveguide; Plasmonic sensor; Plasmonic to dielectric mode converter; Refractive index sensor
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2023.112601

Herein a numerical analysis is performed to explore the conversion efficiency of mode converters for a plasmonic waveguide (WG). The major concern of metal-insulator-metal (MIM) WG devices is the efficient coupling of light to the sub-nano scale WG from an external source. In previous studies, this issue has not been usually investigated. As a result of which the experimental demonstration of MIM WG-based devices is not advanced so far. We proposed a dielectric-to-plasmonic mode converter (DPMC) in the form of a tapered WG to couple the light into the MIM WG and a plasmonic-to-dielectric mode converter (PDMC) to collect the light out of the plasmonic WG. The overall conversion efficiency of the 5000 nm long device is ∼ −1.6 dB. Furthermore, a MIM WG-based sensor is designed by integrating a circular hollow cavity for refractive index sensing applications. The sensitivity and figure of merit of the proposed device are 1132.14 nm/RIU and 48.17 RIU−1, respectively. We consider this study will pave a way for the accomplishment of highly integrated plasmonic sensors based on MIM WGs. •A metal-insulator-metal waveguide plasmonic sensor with integrated mode converters.•Conversion efficiency of the device is ∼ −1.6 dB.•Refractive index sensor which offers a sensitivity and FOM of 1132.14 nm/RIU and 48.17 RIU−1, respectively.