D-shaped silicon core fiber-based surface plasmon-resonance refractive index sensor in 2  µm

Abstract

In this paper, we propose a D-shaped silicon core fiber sensor based on surface plasmon resonance within the 2 µm range. Au layer coating on the D-shaped side-face of silicon core fiber acts as a plasmonic active metal. By using the limited element methods, the sensing properties of the proposed sensor are investigated, and an average sensitivity up to 2650 nm/RIU with a resolution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>3.776</mml:mn> </mml:mrow> <mml:mo>×</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">R</mml:mi> <mml:mi mathvariant="normal">I</mml:mi> <mml:mi mathvariant="normal">U</mml:mi> </mml:mrow> </mml:math> is obtained for the analyte of different refractive indices varies from 1.25 to 1.6. In the investigated simulation, we used real parameters of liquid (e.g., <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">C</mml:mi> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mn>4</mml:mn> </mml:msub> </mml:mrow> </mml:math> liquid and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">C</mml:mi> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math> ) in our simulations for being closer to reality. In addition, the Au coating layer and analyte are placed on the D-shaped side-face of the proposed fiber sensor; hence, this structure does not need to fill the voids. Thus, it is easy to fabricate and put to use. Also, the wavelength band in 2 µm is far from the optical communication band, which means the proposed sensor could be connected with a fiber network without any influence and crosstalk.

Topics & Concepts