Tunable multiple Fano resonances based on a plasmonic metal-insulator-metal structure for nano-sensing and plasma blood sensing applications

Orthogonal mode couplers for plasmonic chip based on metal-insulator-metal waveguide for temperature sensing application

In this work, a plasmonic sensor based on metal-insulator-metal (MIM) waveguide for temperature sensing application is numerically investigated via finite element method (FEM). The resonant cavity filled with PDMS polymer is side-coupled to the MIM bus waveguide. The sensitivity of the proposed device is ~ - 0.44 nm/°C which can be further enhanced to - 0.63 nm/°C by embedding a period array of metallic nanoblocks in the center of the cavity. We comprehend the existence of numerous highly attractive and sensitive plasmonic sensor designs, yet a notable gap exists in the exploration of light coupling mechanisms to these nanoscale waveguides. Consequently, we introduced an attractive approach: orthogonal mode couplers designed for plasmonic chips, which leverage MIM waveguide-based sensors. The optimized transmission of the hybrid system including silicon couplers and MIM waveguide is in the range of - 1.73 dB to - 2.93 dB for a broad wavelength range of 1450-1650 nm. The skillful integration of these couplers not only distinguishes our plasmonic sensor but also positions it as a highly promising solution for an extensive array of sensing applications.

Silicon-tapered waveguide for mode conversion in metal-insulator-metal waveguide-based plasmonic sensor for refractive index sensing

In this study, we have undertaken a comprehensive numerical investigation of a refractive index sensor designed around a metal-insulator-metal (MIM) plasmonic waveguide. Our approach utilizes the finite element method to thoroughly analyze the sensor's performance. The sensor's configuration utilizes a ring resonator design, which has been slightly modified at the coupling segment. This modification enhances the efficiency of light coupling between a bus waveguide and the ring resonator, particularly at the resonance wavelength. This strategic adjustment significantly improves the device's extinction ratio, a critical factor in its functionality. Remarkably, the sensitivity of this sensor is determined to be approximately 1155.71 nm/RIU, while it possesses a figure of merit of 25.9. Furthermore, our study delves into the intricate mechanism governing the injection of light into the nanoscale MIM waveguide. We achieve this through the incorporation of silicon-tapered waveguides, which play a pivotal role in facilitating the transformation of a dielectric mode into a plasmonic mode, and vice versa. Ultimately, the findings of this research hold significant promise for advancing the field of plasmonic sensing systems based on MIM waveguide technology. The insights gained here pave the way for the practical realization and optimization of highly efficient and precise plasmonic sensors.

Tunable electromagnetically induced absorption based on coupled-resonators in a compact plasmonic system

Electromagnetically induced absorption (EIA) exhibits abnormal dispersion and novel fast-light features, making it a crucial aspect of nanophotonics. Here, the EIA phenomenon is numerically predicted in a compact plasmonic waveguide system by introducing a slot resonator above a square cavity. Simulation results reveal that the EIA response can be easily tuned by altering the structure's parameters, and double EIA valleys can be observed with an additional slot resonator. Furthermore, the investigated structures demonstrate a fast-light effect with an optical delay of ∼ -1.0 ps as a result of aberrant dispersion at the EIA valley, which enable promising applications in the on-chip fast-light area. Finally, a plasmonic nanosensor with a sensitivity of ∼1200 nm/RIU and figure of merit of ∼16600 is achieved based on Fano resonance. The special features of our suggested structure are applicable in realization of various integrated components for the development of multifunctional high-performance nano-photonic devices.

Pressure and temperature dual-parameter optical sensor based on the MIM waveguide structure coupled with two T-shaped cavities

This paper elaborates on the design and simulation of a multifunctional optical sensor that features simultaneous detection of pressure and temperature, which is based on the metal-insulator-metal waveguide structure with two T-shaped resonant cavities. Depending on the simulation findings, pressure and temperature can be measured separately by two T-shaped cavities at different Fano resonance wavelengths. As the pressure applied to the upper T-shaped cavity increases, the resonance wavelength first shifts linearly due to the slight deformation of the cavity, and the maximum pressure sensitivity reaches 12.48 nm/MPa. After the pressure exceeds a threshold, the relationship between pressure and resonance wavelength transforms into a quadratic polynomial. In the lower T-shaped cavity, solid polydimethylsiloxane is sealed as a thermal-sensitive material, effectively preventing material overflow brought on by structural micro-vibration under pressure, and its high thermo-optical coefficient prompts a temperature sensitivity of 0.36 nm/°C. Furthermore, by optimizing the choice of Fano resonances, pressure and temperature can be sensed independently without mutual interference. The designed sensor provides extensive application possibilities for scenarios where multiparameter monitoring is required.

Digital coding Fano resonance based on active plasmonic metamaterials

A novel approach that employs active plasmonic metamaterials to create a digital coding Fano resonator is proposed, to the best of our knowledge. The meta-device consists of three concentric spoof localized surface plasmon (LSP) resonators and three positive-intrinsic-negative (PIN) diodes positioned at three slits located in the middle and inner LSP resonators. Four Fano resonant modes can be independently switched by controlling the biased voltage applied to the three diodes. This provides a means for encoded modulation of multiple Fano resonances in metamaterials, which could have broad applications in fields such as multiway sensing, plasmonic circuits, and switching. We experimentally demonstrate the effectiveness of the proposed approach, which offers promising potential for practical implementation.

Quadruple Fano resonances in MIM waveguide structure with ring cavities for multisolution concentration sensing

In this paper, a metal-insulator-metal (MIM) waveguide structure is proposed to produce quadruple Fano resonances, which is composed of a side-coupled elliptical cavity, a half-ring cavity, a half-ring cavity with an opening, and a bus waveguide with a circular barrier. The simulation results show that the resonant wavelengths of the quadruple Fano resonances can be almost independently tuned by changing the structural parameters of the three cavities. The refractive index sensing based on different cavities is discussed, and the maximum sensitivity is 1048.6 nm/RIU with an excellent linear-sensing relationship. Finally, the simultaneous multisolution concentration sensing is demonstrated, and the sensitivities are 0.138n m L ^-1 g ^-1 for the plasma concentration, 0.120n m L ^-1 g ^-1 for the glucose solution concentration, and 0.180n m L ^-1 g ^-1 for the N H ₄ C l solution concentration. The results are conducive to promoting the applications of MIM waveguide structures in integrated optical sensing.

MIM waveguide system with independently tunable double resonances and its application for two-parameter detection

A metal-insulator-metal (MIM) waveguide system consisting of a MIM waveguide, a ring cavity, and a semi-ring cavity is proposed. Using the finite element method, the transmission characteristics of the MIM waveguide system are discussed under the different geometry parameters. By detecting the resonance wavelength and varying the refractive index, the sensing performance of the MIM waveguide system is analyzed. The proposed structure can be used as a refractive index sensor with the maximum sensitivity of 2412 nm/RIU. Due to isolating the ring cavity and semi-ring cavity, the independent tuning of double resonances can be realized by changing the refractive index of the insulator in the ring cavity or the semi-ring cavity. Benefiting from two independent refractive index sensing modes, the structure with two isolated resonators can realize the simultaneous measurement of glucose solution concentration and blood plasma concentration. The sensitivity of glucose solution sensing in the ring cavity is 0.13133 nm/(g/L). Meanwhile, the blood plasma concentration detection in the semi-ring cavity is realized with the sensitivity of 0.358 nm/(g/L). The system with two isolated cavities has the potential to be used as an efficient nano sensor, which can achieve simultaneous measurement of two parameters.

Multiparameter Sensing Based on Tunable Fano Resonances in MIM Waveguide Structure with Square-Ring and Triangular Cavities

In this paper, a metal–insulator–metal (MIM) surface plasmon waveguide structure is proposed and numerically investigated. It is composed of a square-ring cavity with a silver baffle, an isosceles triangle cavity, and a bus waveguide with a silver baffle. The results show that the structure can produce triple Fano resonances that can be independently tuned by changing the structural parameters. The detection of refractive indexes at different positions in the structure was also accomplished, with a maximum sensitivity of 2259.56 nm/RIU. On the basis of this, the simultaneous measurement of multiple parameters (plasma concentration and glucose concentration) was performed. The numerical simulation results are beneficial to the applications of MIM waveguide structure in nanosensing and biosensing with time-sharing or simultaneous measurement of multiple parameters.