# Enhanced Sensitivity in D-Shaped Optical Fiber SPR Sensor via Ag-α-Fe2O3 Grating

## TL;DR

This paper presents a D-shaped optical fiber sensor with improved sensitivity using a silver-hematite composite grating for better detection in biomedical and environmental applications.

## Contribution

The novel contribution is the optimized Ag-α-Fe2O3 grating design that enhances electric field confinement and sensor sensitivity.

## Key findings

- A 45 nm silver layer and 12 nm α-Fe2O3 layer provide optimal electric field confinement.
- A 30 nm grating gap width maximizes sensitivity through enhanced localized surface plasmon resonance.
- A 0.5 μm residual cladding thickness balances detection accuracy and sensitivity.

## Abstract

The development of high-performance optical fiber sensors based on surface plasmon resonance (SPR) represents a significant advancement in precision detection technology, particularly for biomedical and environmental monitoring applications requiring real-time response and minimal sample consumption. This research conducts a systematic numerical investigation of a D-shaped fiber SPR sensor incorporating an optimized silver-hematite (Ag-α-Fe2O3) composite grating structure. Through comprehensive finite element simulations and parameter analysis, we demonstrate that controlling the silver layer thickness at 45 nm while maintaining the α-Fe2O3 thickness at 12 nm achieves optimal electric field confinement. The grating gap width optimization at 30 nm enables maximum sensitivity through enhanced localized surface plasmon resonance effects, while the residual cladding thickness of 0.5 μm provides the ideal balance between detection accuracy and sensitivity. The research establishes fundamental design principles for high-performance SPR sensors by elucidating the critical relationships between geometric parameters and sensing characteristics, providing valuable insights for developing next-generation sensors with enhanced performance for advanced sensing applications in environmental monitoring and medical diagnostics.