Graphene-assisted tunable D-shaped photonic crystal fiber sensor in the visible and IR regions

Abstract

A simple design of a D-shaped photonic crystal fiber sensor with 10 layers of graphene on the surface plasmon of gold is proposed for tuning refractive index (RI) sensitivity in the visible and IR regions. The proposed structure has been simulated by optimizing the mesh size and the method of finite-difference eigenmode. By tuning the chemical potential of graphene ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>μ</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:mrow> </mml:math> ), we realize tunable and enhanced RI sensing for a wide RI range from 1.35 to 1.42. The maximum wavelength sensitivities of the proposed sensor are 5200 nm/RIU, 6000 nm/RIU, and 7500 nm/RIU for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi>μ</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:mrow> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.8</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">v</mml:mi> </mml:mrow> </mml:mrow> </mml:math> , 1.0 ev, and 1.2 ev, respectively. Further, sensor characteristic parameters such as amplitude sensitivity, resolution, and figure of merit have been investigated for different chemical potentials. All dramatic changes in sensor parameters show an advancement plan to control and tune RI-based optical sensors assisted by graphene.