Highly Sensitive SPR Sensor Based on Hybrid Coupling Between Plasmon and Photonic Mode

In this letter, we propose a new configuration of surface plasmon resonance sensor based on hybrid coupling between long-range surface plasmon polariton (LRSPP) and dielectric planar waveguide mode (WGM) for ultrasensitive refractive index sensing. The multilayer Otto configuration supports both LRSPP and photonic WGM. Under phase matching condition, these two modes can be dramatically coupled with each other forming hybrid modes and consequently splitting the resonance. By optimizing the structure parameters, an intensity sensitivity as high as 3081/RIU is achieved, which corresponds to 1.2-fold enhancement comparing to the conventional LRSPP sensor. Moreover, the sensor can be modified for detecting the analyte according to different targeting refractive index ranges by simply replacing the dielectric medium.