Optics and Photonics Society of Iran

In this paper, by using trapezius gold grating that covered by a graphene monolayer a surface Plasmon’s were formed in the near infrared region. By using the wavelength dependence of the Plasmon’s resonance on the optical properties of deionization water that is use for making biomolecules solution has been investigated. a biosensor in near infrared were suggested. By introducing the sensitivity coefficient of S=Δλ /Δn, and the quality factor Q=S/FWHM in refractive index from n=1.333 and Δn=0.001 sensitivity of the structure for deionization water was calculated. Then, the effect of trapezoidal and square grating on the sensor sensitivity and Quality was investigated and the best value for trapezoidal grating 900 nm/RIU and 1731, was reported respectively.