Exploration of Illicit Drug Detection Based on Goos–Hänchen Shift

Abstract

Amidst the escalating issue of drug abuse, an urgent need for effective illicit drug detection methods has arisen. This paper introduces a novel optical approach utilizing the Goos–Hänchen Shift (GHS) to explore the possibility of on-site rapid detection of illicit drugs. Delving into the mechanisms, light absorption and attenuation in biological samples are considered through absorption and attenuation coefficients, establishing connections between complex refractive indices, complex dielectric constants, and GHS. A self-assembled GHS detection system measured GHS values across various samples: ultrapure water, serum, methamphetamine, serum–methamphetamine, heroin, and serum–heroin. These experiments unveiled substantial GHS variations among the samples. Refractive indices for serum, serum–methamphetamine, and serum–heroin samples were computed using GHS values and sample extinction coefficients, highlighting GHS’s remarkable sensitivity to refractive index variations as a high-sensitivity refractive index sensing technology. The correlation between the dielectric constant and GHS was explored, yielding refractive indices for pure solutes—serum, methamphetamine, and heroin—of 1.66300, 1.51300, and 1.62300, respectively. Notably, the dielectric constants for these solutes were 2.76557, 2.28917, and 2.63413, emphasizing the dielectric constant’s discriminative potential in identifying illicit drugs. In conclusion, these findings suggest that GHS holds promise for distinguishing various illicit drug types, charting an innovative path for illicit drug detection.