Excitation of Multiple Fano Resonances in a Plasmonic Device and Carcinoma Detection

A plasmonic device is studied for the induction of 11 Fano resonances (FRs) in the transmittance spectrum. Initially, a circular ring resonator side coupled to metal-insulator–metal (MIM) waveguide with inclined slit yields 11 resonances in the spectrum. Out of these 11 resonances, seven are induced to the FRs and the rest four resonances remained to be the window resonances. The window resonances are further transformed to FRs by sectorizing the ring resonator. The sectorized ring resonator comprises four distinct regions for surface plasmon localization and acts as multiple indirect pathways. The sectorization is also beneficial for tight confinement of the surface plasmon polaritons (SPPs), which aids in achieving the full-width at half minima (FWHM) to 0.35 nm. The minimal FWHM overshoots the quality factor and figure of merit (FOM) to 1598.57 and
$1520~\mathrm {RIU}^{-1}$
, respectively. The sectorization increases the number of resonances by a factor of 1.6 and an FWHM and a quality factor to −42.8% and 28.3%, respectively. This improvement is obtained with respect to the initial circular ring resonator. These spectral signatures of the proposed device overcome the tradeoff between the number of FR and performance parameters. The proposed device operates over the wavelength range of
$\lambda $
= 400–1100 nm providing the sensitivity of
$S =\mathbf {902}~\mathrm {nm}/\mathrm {RIU}$
in the investigated refractive index range of
$n =1.00$
–1.05. This applies to the proposed device for the detection of three distinct types of cancer namely, blood cancer, cervical cancer, and skin cancer using the refractive indices of the corresponding cancer types. The sensitivity and FOM of the proposed device for cancer detection are obtained as
$S/\mathrm {FOM} = 892.85/1524.48, 882.5/1553.57$
, and
$900/1492.85~\mathrm {nm}/\mathrm {RIU}/\mathrm {RIU}^{-1}$
for blood, cervical, and skin cancer, respectively.