High-resolution biosensing with C-band guided mode Fano resonance in an all-dielectric structure

An all-dielectric Fano resonance sensor is proposed, and its sensing characteristics are numerically investigated in the near-infrared region. The proposed device comprises two planar waveguides and a grating. The coupling between high- and low-quality-factor guided modes of the waveguides leads to a sharp Fano resonance at the optical communication wavelength of . Owing to the transparency of constituent dielectric layers in the near-infrared region, a sharp, low-loss Fano resonance appears in the reflection spectrum, which is favorable in sensing applications. The proposed sensor can detect small changes in the refractive index of the sensing medium as low as . The high sensitivity of a structure is promising in biochemical applications, such as measuring the refractive indices of organic solvents, the level of water content in ethanol and aqueous solutions, and blood glucose levels. The refractive index sensitivity is as high as λ =1550nm, and a figure of merit of Δ n =0.001 is achieved.