Analytical Methods of Equivalent Circuit Model and Transmission Matrix for a Plasmonic Switch with Sensing Capability in
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Analytical Methods of Equivalent Circuit Model and Transmission Matrix for a Plasmonic Switch with Sensing Capability in Near-Infrared Region Mohamad Nejat 1 & Najmeh Nozhat 1 Received: 6 December 2019 / Accepted: 31 March 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this paper, the simultaneous switching and sensing capabilities of a compact plasmonic structure based on a conventional rectangular hole in a silver film are proposed and investigated. The proposed structure has ultrahigh sensitivity up to 3000 nm/ RIU and high figure of merit of 170 RIU−1. Also, the simulation results show the potential of the presented refractive index sensor to detect malaria infection, cancer cells, bacillus bacteria, and solution of glucose in water. Simultaneously, by changing the incident lightwave polarization, the structure behaves like a plasmonic switch, which has high extinction ratios of 15.81, 31.20, and 25.03 dB at three telecommunication wavelengths of 850, 1310, and 1550 nm, respectively. The ultrafast response time of 20 fs is achieved for the wideband application of the switching capability at the wavelength range of 1056 to 1765 nm. Moreover, the equivalent circuit model and transmission (ABCD) matrix methods are derived to validate the simulated results. Simple design, good agreement between the numerical and analytical results, biomedical applications, ultrahigh sensitivity, and ultrafast performance of the proposed structure help this idea to open up paths for design and implementation of other multi-application plasmonic devices in near-infrared region. To the best of our knowledge, the mentioned analytical methods have not been studied former at near-infrared wavelengths. Therefore, the achievements could pave the way for verifying the simulation results of plasmonic nanostructures in future investigations. Keywords Biomedical . Circuit model . Near-infrared . Plasmonic . Polarization-multiplexing . Sensor . Switch . Transmission matrix
Introduction Plasmonic structures have potential to overcome the diffraction limit utilizing surface plasmons (SPs). SPs are strong interactions between the free electrons of metal and incident electromagnetic wave at the interface of metal and dielectric. Therefore, miniaturization and light guiding in deep subwavelength structures can be realized by SPs, which contain surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) [1–3]. When the metal-dielectric interface is not large enough for propagation of SPs (SPPs), they oscillate at their own place (LSPs) [4]. In the past few years, many SP-based devices have been suggested and studied such as filters [5], absorbers [6], sensors [7], and optical switches [8]. * Najmeh Nozhat [email protected] 1
Department of Electrical Engineering, Shiraz University of Technology, Shiraz 7155713876, Iran
Surface plasmons have been utilized to enhance optical transmission, which was studied for the first time by Ebbesen in 1998 [9]. The transmission component of electromagnetic wav
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