Highly sensitive Goos–Hänchen shift surface plasmon resonance sensor with tin selenide allotropes

A Goos–Hänchen shift (GHS) surface plasmon resonance (SPR) refractive index sensor with the employment of two-dimensional tin selenide (SnSe) is proposed. Both the magnitude and sign of GHS can be controlled with the number of SnSe layers. It is found that the magnitude of GHS can be significantly enhanced with the optimum configurations of α-SnSe and ɛ-SnSe integrated SPR structures, which is about 2.72 and 3.87 times higher than that of the optimized conventional SPR structure, respectively. A highly sensitive refractive index sensor based on the enhanced GHS is proposed, which provides a 6.4-fold improvement in sensitivity compared to the conventional SPR structure. These results offer a promising approach to achieve significantly enhanced GHS, and the designed GHS-SPR sensor could provide potential applications in chemical sensing and biosensing.