摘要： Most surface plasmon resonance (SPR) based photonic crystal fiber (PCF) sensors have been designed to detect the analyte refractive index (RI) ranging from 1.33?1.41. In this paper, we propose a new approach to extend the detection range of the sensor, and it can be fabricated with the existing fabrication techniques. Contrary to the existing PCF based sensors, our designed sensor is based on an air-core PCF where analyte is placed to the core of the PCF through a vertical side opening channel and is able to detect RI of the analyte higher than that of the PCF background. We use a chemically stable plasmonic material (i.e., gold), where the plasmonic material and analyte are placed in such a way that there is no direct contact between them, thus reducing the interference effect. According to our simulation, we show that the spectral sensitivity and resolution are achieved as 11,700 nm/RIU and 8.55×10–6 RIU, respectively, for the analyte RI of 1.42. We believe that our proposed sensor can be used to detect highly active chemical and biological liquid samples.