研究目的
Investigating the use of guided resonances in a photonic crystal slab (PCS) for terahertz refractive index sensing.
研究成果
The study demonstrates a terahertz refractive index sensor based on guided resonance in a photonic crystal slab, achieving a sensitivity of 23.08 GHz/RIU. The resonance frequency shifts linearly with the refractive index of analytes, allowing for the prediction of refractive indices with high sensitivity. The results suggest that PCS structures offer a simple, easy-to-use method for high-sensitivity refractive index sensing in the terahertz regime.
研究不足
The sensitivity of the proposed PCS structure, while competitive, still needs improvement compared to some previous reports. Additionally, the fabrication difficulty increases with decreasing slab thickness, which could limit the practical application of thinner structures.
1：Experimental Design and Method Selection:
The study employs a numerical simulation approach using the 3D finite-difference-time-domain (FDTD) method to analyze the guided resonance in a two-dimensional PCS. The PCS consists of a square lattice of air holes in a silicon slab on a quartz substrate.
2：Sample Selection and Data Sources:
The structural parameters of the PCS (hole radius r, lattice constant a, and slab thickness t) are varied systematically to study their effects on the guided resonance.
3：List of Experimental Equipment and Materials:
The simulation setup includes a unit cell of the PCS with periodic boundary conditions (PBCs) in the x- and y-directions and perfectly matched layers (PMLs) at the top and bottom surfaces. A normally incident plane wave with an electric field linearly polarized along the y-direction is used for excitation.
4：Experimental Procedures and Operational Workflow:
The effects of the PCS structural parameters on the guided resonance are investigated by varying each parameter while keeping the others constant. The sensitivity of the PCS sensor is calculated for different structural parameters to optimize the geometry for higher sensitivity.
5：Data Analysis Methods:
The transmission spectra of the PCS are analyzed to determine the resonance frequency shifts due to changes in the refractive index of analytes. A linear model is fitted to the resonance frequency versus refractive index data to calculate the sensitivity.
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