2025/10/18 by Osama Haramine Sinan, Ifaz Ahmed Adan, Sinan, Osama Haramine +4
Engineering · #Advanced Fiber Optic Sensors #FOS: Physical sciences #Optics (physics.optics) #Photonic Crystal and Fiber Optics #Plasmonic and Surface Plasmon Research
paper · pdf · doi:10.48550/arxiv.2510.16480
openalex publication_date 2025/10/18 · openalex created_date 2025/10/22 · openalex updated_date 2026/07/28
Surface plasmon resonance (SPR) sensors built on photonic crystal fibers (PCFs) have recently become a promising category of optical sensing platforms. This is primarily due to their high sensitivity, compact structural design and ability to work with a wide variety of analytes. The overall sensing performance can significantly be enhanced by carefully tailoring the fiber geometry to strengthen the coupling between the guided core mode and the plasmon mode. This study designs and thoroughly investigates a polarization-dependent SPR-based PCF sensor that delivers strong mode coupling, wide detection range and high refractive-index (RI) sensitivity using finite element method (FEM). In the proposed configuration, air holes with different diameters and a rectangular core slot are used to create birefringence along with four outer microchannels coated with a 30 nm gold film create distinct plasmonic regions that support multiple resonances. The simulated results yield maximum wavelength sensitivities of 77500 nmRIU-1 and 92500 nmRIU-1, along with amplitude sensitivities of 3930 RIU-1 and 3139 RIU-1 and figures of merit of 517 RIU-1 and 356 RIU-1 for the x- and y-polarizations respectively, over an analyte RI range of 1.32-1.42. The parametric study verifies that the design is highly tolerant to fabrication deviations and the coupling behavior is primarily sensitive to the smallest air holes and the height of the core slot. Since the sensing region is external, analytes can be reused conveniently. Consequently, the proposed sensor provides a compact, highly sensitive and practically realizable platform for biochemical and chemical sensing applications.