Square structured photonic crystal fiber based THz sensor design for human body protein detection

In this manuscript, a squared hollow-core photonic crystal fiber-sensor is introduced, which can be used for efficient amino acid investigations using THz waves. Amino acid identification is crucial in medical science, particularly in the drug discovery. The performance analysis has been conducted using the finite element method (FEM) based the COMSOL MULTIPHYSICS software package, and important waveguide properties have been assessed elaborately for five essential amino acids in a wide range of THz frequencies at different core dimensions. The analysis shows that the proposed model exhibits an extraordinarily high sensitivity of 99.98% and remarkably low confinement loss of 4.72 × 10^–22 cm⁻¹ for tryptophan, the rarest of the essential amino acids found in proteins. The excellent sensing capabilities are achieved by introducing two hollow square air cavities surrounded by four rectangular air channels in the cladding. The fabrication of the sensor is achievable using the extrusion technique with 3D printing, which is also discussed in detail.