Self-referenced refractive index sensor utilizing Tamm plasmon in a photonic quasicrystal

The proposed work presents a theoretical design for a self-referenced refractive index sensor based on coupled Tamm Plasmon polariton (TPP) in a photonic quasi-crystal structure. The sensor structure is composed of a sub-wavelength analyte layer sandwiched between two metals capped distributed Bragg reflectors arranged in a Fibonacci sequence. The optical properties of the coupled TPP mode are investigated using the transfer matrix method. The reflection spectra characteristics of the proposed sensor exhibit two distinct reflectivity dips within the photonic band gap of the Fibonacci sequence photonic quasi-crystal. The lower wavelength reflection dip remains unchanged when the analyte refractive index is altered, serving as a reference wavelength. On the other hand, the higher resonance wavelength reflection dip shows significant variation with changes in the sensing layer's refractive index. The performance of this sensing configuration is analyzed by studying the dispersion properties associated with the resonance wavelength of the symmetric mode and various sensor parameters. The numerical investigations demonstrate a sensitivity fluctuation ranging from 65 to 240 nm/RIU and a figure of merit varying from 7 to 23 RIU⁻¹. The Quality Factor ranges from 73 to 85, with detection accuracy varying from 0.095 to 0.115 nm⁻¹. The Limit of Detection ranges from 2 × 10^–6 to 6 × 10^–6, and the Resolution changes from 10 to 11 in the visible band of the spectrum. Based on these findings, the proposed sensor geometry shows potential for various applications, including biosensing, and can operate in the visible, near-infrared, and far-infrared regions of the electromagnetic spectrum.