Multifunctional terahertz device with angular resilience for biomedical sensing and polarization conversion

Abstract

The demand for high-performance devices capable of both electromagnetic wave manipulation and biomedical detection has intensified with the growth of terahertz technologies. However, most existing devices are designed for a single function, either polarization control or biosensing which limits their utility in integrated systems. Addressing this challenge, we introduce a cost-effective terahertz device that seamlessly integrates broadband cross polarization transformation with precise refractive index sensing, all within a fabrication-friendly structure. Utilizing aluminum patterned resonators on a Rogers RT5870 dielectric layer, the device delivers a polarization conversion ratio above 94% across a wide spectral window of 3.492 THz with peak conversion efficiencies exceeding 99.9% at multiple resonances and retains stable performance at oblique incident angles up to 40°. Simultaneously, it functions as a refractive index sensor reaching a peak sensitivity of 1.35 THz RIU⁻¹ and effectively distinguishes between healthy and diseased biological samples including blood, cervical and skin tissues. Compared to state-of-the-art designs which typically specialize in either polarization modulation or biosensing alone, the proposed device stands out for its dual functionality, high sensitivity and ultra-broadband performance. This work fills a rarely addressed research gap by delivering a single device capable of both advanced polarization control and reliable biomedical diagnostics, paving the way for multifunctional terahertz systems.