Numerical exploration of external sensing scheme based photonic crystal fiber surface plasmonic sensor with different noble plasmonic materials and their alloys

The selection of appropriate plasmonic material is extremely crucial for getting good sensing performance from photonic crystal fiber-based surface plasmon resonance (PCF-SPR) sensors. The numerical investigation of PCF-SPR sensors is still limited to conventional plasmonic materials in most existing studies. Recent researches show that some alloys can also be potential candidates as plasmonic materials for their remarkable plasmonic characteristics. This article presents a numerical analysis of a simple designed external sensing scheme based PCF-SPR sensor employing different noble plasmonic materials and their alloys. The sensor's design is kept very simple to ease the fabrication complexity, and the sensing ingredient is placed outside of the main structure. To investigate the sensing performance of the sensor, we have chosen gold, silver, and copper as noble plasmonic materials and gold-silver (30 %–70 %), gold-silver (70 %−30 %), and copper-zinc (90 %−10 %) as alloys. From the obtained results, it is observed that the reported sensor shows maximum amplitude sensitivity (AS) of 9759.00 RIU−1 and figure of merit (FOM) of 923.07 RIU−1 when the silver coating is used. Moreover, the reported sensor shows maximum spectral sensitivity (SS) of 26,000 nm/RIU and resolution of 3.84 × 10-6 with copper-zinc (90 %−10 %) alloy. Because of its highly sensitive performance, this sensor can be an impressive appliance for the identification of organic substances, biological fluids, and samples.