Highly sensitive Borophene-metal-Si based multilayered Terahertz frequency spectrum based refractive index sensor

Abstract

We presented the numerical investigation of a multilayered borophne-metal-Si-based refractive index sensor for the wide range of the THz frequency. The proposed structure is worked for the frequency range of 1 to 15 THz. The structure is formed to identify reflectance variation, resonating frequency and other physical parameters over the broad frequency spectrum. The overall structure is simulated using FEM (Finite element method) computational techniques with a periodic boundary condition-based two-port model. The resonance effect of the structure is also investigated for the different shapes of the top metal resonator structure, which significantly influences the overall frequency shift. The proposed structure is investigated for the X and Y polarized input incident condition for the entire frequency band where the oblique angle incident stability is observed up to 80°. The proposed structure offers the maximum variation in sensitivity up to 3.5 THz/RIU (∼ 11600 nm/RIU) for X-polarized and 5.5 THz/RIU (∼10600 nm/RIU) for Y-polarized incident wave conditions. We have applied the artificial neural network algorithm (ANN) to predict the overall behaviour of the structure from the data points generated in the simulated results. We used the Relu optimizer to train the model, generating promising results for our collected data. The machine learning model gives RMSE = 0.049422, MAE = 0.018531, MSE = 0.00328 and R2 = 0.93768 for the testing data set. Similarly, the model generated the minimum RMSE values = 0.045955, MAE = 0.017392, MSE = 0.00295, and R2 = 0.97673 for the training data set for 2500 epochs. The proposed results in the manuscript give the future scope to design borophene a wide range of refractive index (RI) sensor designs used in biosensors, gas sensors and other environment sensors where the refractive index range is between 1 and 2.4.