Enhanced sensitivity of silicon-on-insulator surface plasmon interferometer with additional silicon layer

t is theoretically found that by adding a thin dielectric layer (35 nm) on top of our previously proposed surface plasmon interference (SPI) biosensor in silicon-on-insulator (SOI) a sensitivity enhancement is obtained of up to 2500 nm/RIU (refractive index unit) for short sensors. At the same time, the corresponding figure of merit (FOM) is as high as 237 (RIU-1). This improvement is caused by the reduction in group index difference between the two interfering modes