High quality factor D-type fiber surface plasmon resonance (SPR) sensor based on the modification of gold nanoshells

A D-type optical fiber surface plasmon resonance (SPR) sensor based on gold film and Au nanoshells is described. The sensor has a smaller full width at half maximum (FWHM) and a higher quality factor. The influence of the coupling effect between the Au nanoshells and gold film with different internal and external diameter ratios on the sensor was investigated by the finite element method. The simulation results show that the coupling effect between the SPR of the gold film and the localized surface plasmon resonance (LSPR) of the Au nanoshells effectively improved the electric field strength of the sensing region. The refractive index measurements show that the sensitivity of the D-type fiber/gold film/Au nanoshell (50/40 AuNS) SPR sensor is 3064 nm/RIU, which is 993 nm/RIU higher than for the D-type fiber/gold film SPR sensor. The D-type fiber/gold film/Au nanoshell (50/40 AuNS) SPR sensor also provides good linearity with a value of 99.4%. The sensor reported in this paper can be used for reference in the development of high performance biosensors.