Pressure sensor based on multiple Fano resonance in metal–insulator–metal waveguide coupled resonator structure
Fang Chen, Wen‐Xing Yang
Abstract
This paper presents a plasmonic pressure sensor via an optical metal–insulator–metal (MIM) waveguide structure. The proposed pressure sensor is composed of a ring resonator, a stub, and a U-shaped resonator coupled to the bus waveguide. The finite-difference time-domain method (FDTD) is used to study the Fano resonance (FR) characteristics and magnetic field distributions. Results show that the Fano line shapes can be independently tuned by the geometrical parameters. When pressure is exerted on the U-shaped resonator layer, the deformation leads to the shift of the resonant wavelength. The calculated maximum pressure sensitivities are 10.96 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>10</mml:mn> </mml:mrow> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>.5</mml:mn> </mml:mrow> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">M</mml:mi> <mml:mi mathvariant="normal">P</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> </mml:mrow> </mml:mrow> </mml:math> for FR 2, and FR 3, respectively ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">M</mml:mi> <mml:mi mathvariant="normal">P</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> </mml:mrow> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mn>10</mml:mn> <mml:mn>6</mml:mn> </mml:msup> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">P</mml:mi> <mml:mi mathvariant="normal">a</mml:mi> </mml:mrow> </mml:mrow> </mml:math> ). The good linear relationship between the pressure and resonance wavelength indicates that the proposed nano-scale structure can find potential applications in the fields of nano-biosensing and biomedical sensing.