A comprehensive framework for optimizing dual plasmonic LSPR-PCF sensors: The role of displacement angle

Abstract

The integration of Localized Surface Plasmons in Photonic Crystal Fibers has led to the emergence of intriguing sensor designs with advantageous properties. Inspection of such sensor designs reveals an unexplored question: whether the Displacement Angles between plasmonic layers affect the overall performance. This comparative analysis aims to comprehensively report the influence of Displacement Angle between dual plasmonic layers in LSPR-PCF sensors, whilst retaining the same sensor cross-section. The analysis has been done for four discrete angles of 0°, 60°, 120° and 180°. Each angular variant has been optimized individually through layer thickness and airhole diameters; eventually, the best angular variant has been deduced from a novel parameter, the Sensor Performance Mark (SPM). Gold (metal) has been used for the 1st layer and AZO (semiconductor) for the 2nd layer. It is observed that the variation of Displacement Angle can significantly alter the core-loss trajectory as well as the interaction of the surface plasmons with the analyte to be sensed; thus, leading to the difference in performances in respective variations. We anticipate that in the future, more sophisticated fiber optic sensors will be optimized through the Displacement Angle approach, followed by the conventional optimization procedures.