Piezoplasmonic System for Enhanced Photonic Spin Hall Effect for Applications in Optical Refractive Index Sensing

The interplay of intense spin-orbit interactions (SOIs) with plasmonic and piezoelectric surfaces offers a promising solution for precise control over polarization states and wavefront shaping. Reconfigurable beam manipulation, driven by variable voltage and SOIs, has emerged as a key focus in advancing optical systems. Despite this potential, the mechanical rigidity of piezoelectric materials and their inherently static optical properties post-fabrication present significant challenges, restricting their adaptability and dynamic functionality. This study explores the integration of plasmonic and piezoelectric materials to overcome these limitations, enabling voltage-controlled modulation of refractive index and thickness for tunable SOIs. In this manuscript, the photonic spin Hall effect (PSHE), arising from the SOI of light, is demonstrated in a layered structure consisting of silver (Ag), the piezoelectric material PMN-PT, and an additional Ag layer. By applying a voltage bias (V_B) of –5.874 V, left-hand circular polarization achieves a maximum conventional spin dependent shift (CSDS) of 143.357 μm for a PMN-PT layer thickness of 387 nm, outperforming previously reported PSHE studies. Further, the proposed PSHE framework demonstrates potential for antigen or complementary DNA detection, owing to the exceptional tunability of PMN-PT. A spin-dependent sensitivity of 610430.50 μm/RIU is achieved at a refractive index change of Δn = 1 × 10^-3 under a voltage bias of –5.874 V for complementary DNA sensing. Furthermore, the proposed sensor design (str-3) exhibits an extraordinary limit of detection (${\bm{Lo}}{{{\bm{D}}}_{{\bm{sd}}}}$) of 1.638 × 10^-9 degree. RIU/μm, marking a significant advancement in precision optical sensing.