Approach the angular sensitivity limit in surface plasmon resonance sensors with low index prism and large resonant angle

Surface plasmon resonance (SPR) sensors have been studied thoroughly for the past two decades. However, we found that the angular sensitivity in a prism-coupled SPR sensor can be as high as 500 deg/refractive index unit (RIU), which is two times higher than the sensitivity that has ever been achieved in previous studies. Such a high angular sensitivity can be fully achieved by simply choosing a proper low-index prism and a sufficiently large resonant angle for the light signal at an appropriate wavelength with an optimal metal film thickness. A feasible implementation of such an SPR sensor design concept was also proposed, and an even higher sensitivity of 600 deg/RIU can be achieved.