The sensing characteristics of periodic staggered surface plasmon gratings

• The sensitivity reaches about 7029.5 nm/RIU, which is very high in SPPs sensors.
• The sensor has much better linear characteristic than PCF sensors'.
• The excitation of resonance avoids requiring strong condition.
• The staggered design saves space and causes less dielectric loss.

Bragg gratings, because of their favored surface plasmon coupling characteristic, are widely applied in nano-optics. We propose a periodic staggered Bragg gratings structure as a refractive index sensor by the finite element method. The optimized extraordinary optical transmission based on staggered gratings can excite surface plasmon resonance for much larger wavelength. The refractive index can be obtained by detecting the resonant wavelength shift of transmittance peak. This sensor exhibits high sensitivity and favorable linear characteristic in a wide variation interval of refractive index. The simulation results provide a further insight into nano optical sensors.