Nano-Engineered HfO2-Au photonic sensor for ultra-sensitive refractive index detection.

• A novel hafnium dioxide (HfO 2) and gold (Au) based PCF sensor optimized for refractive index measurement in the 1.3 µm to 1.6 µm spectrum. • Geometrically optimized D-shaped fiber geometry to facilitate efficient light-matter interaction and surface plasmon coupling. • Performance metrics including confinement loss (<10–6 dB/m), propagation constant (β) ∼6 × 10⁶, V-Parameter <2.3, and a peak relative sensitivity of 99.05 %. • Precise discrimination in refractive indices ranging from 1.32 to 1.40. • Addressed the practical aspects of fabricating the proposed HfAu-PCF sensor design. In this study, we introduce a novel hafnium dioxide (HfO 2) and thin gold layer based photonic crystal fiber (HfAu-PCF) sensor for refractive index measurement and optimize in the spectrum of 1.3 µm to 1.6 µm. The proposed sensor incorporates a D-shaped geometry for enhanced light-matter interaction, and the core of the fiber is surrounded by periodic air holes to facilitate efficient coupling of the guided mode with surface plasmons. The proposed HfAu-PCF sensor is geometrically optimized using finite element method (FEM) by fine-tuning air hole diameter, core size, layer thickness dimensions of the fiber to achieve performance stability. Leveraging the unique optical properties of HfO 2 and Au, the sensor demonstrates superior performance metrics, achieving confinement loss (<10⁻⁶ dB/m), propagation constant (β) ∼ 6 × 10⁶, V-Parameter < 2.3, a peak relative sensitivity of 99.05 % across the tested wavelength of 1.3 µm to 1.6 µm. Our findings reveal that choosing suitable parameters could lead to further enhancements in sensitivity, making the sensor for applications in bio-sensing, environmental monitoring, and chemical analysis, etc. [ABSTRACT FROM AUTHOR]