Graphene Effect on the Improvement of the Response of Optical Fiber SPR Sensor

In this paper, we present a contribution to the development of a fiber-optic surface plasmon resonance sensor coated with a silver film that is suitable for chemical and biological applications. Indeed, the importance of the choice of the metal deposited on the sensitive zone of the sensor was verified. It has been found that silver-based sensors have better sensitivity. But on the other hand, it suffers from its poor chemical stability. In order to improve sensor stability, a protective layer of graphene was added, and an optimization of the geometrical and physical properties characteristic of the new configuration was presented by using a numerical study. The results obtained show that the sensitivity of the sensor depends on a set of parameters, such as the diameter of the core (<inline-formula> <tex-math notation="LaTeX">${D}$ </tex-math></inline-formula>), the sensitive length (<inline-formula> <tex-math notation="LaTeX">${L}$ </tex-math></inline-formula>), and the thickness of the metal layer (<inline-formula> <tex-math notation="LaTeX">${d}$ </tex-math></inline-formula>) and its nature. The optimal choice of these parameters was fixed for the following values: <inline-formula> <tex-math notation="LaTeX">$D=400~\mu \text{m}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$L=15$ </tex-math></inline-formula> mm, and <inline-formula> <tex-math notation="LaTeX">$d=50$ </tex-math></inline-formula> nm.