▎ 摘　　要

In this paper, we investigate sensitivity enhancement of a graphene based nearly guided-wave surface plasmon resonance (NGWSPR) biosensor in the visible region. The proposed biosensor is optimized using genetic algorithms to obtain the highest sensitivity for a specific wavelength of incident light. The optimized sensitivity of the NGWSPR sensor is compared with a traditional surface plasmon resonance (SPR) biosensor at the wavelength of incident light varied from 400 to 800 nm. The percentage of sensitivity increment of a NGWSPR sensor relative to a traditional SPR sensor is also calculated. As high as 393.3, 542.5, 388.9 or 132.1% sensitivity increment percentage has been demonstrated for an Au, Ag, Cu or Al based NGWSPR sensor. Furthermore, the maximum sensitivity of a NGWSPR biosensor at different wavelength is also investigated and compared. For a NGWSPR sensor based on Au, Ag, Cu or Al, the maximum sensitivity is 225.12, 302.26, 222.04, or 163.78 degrees/RIU showing at 720, 480, 680 or 400 nm respectively.