An Innovative Straight Resonator Incorporating a Vertical Slot as an Efficient Bio-Chemical Sensor

A compact and integrated label-free refractometric bio-chemical sensor based on silicon-on-insulator (SOI) is proposed and comprehensively studied at the telecommunication wavelength of λ = 1550 nm. This device incorporated a three-dimensional (3D) Fabry-Perot cavity in the nano-scale regime with maximum footprint area around 470 × 473 nm2. A resonance shift (Δλres) of 5.2 nm is reported for an ultrathin (5 nm) bio-layer sensing. Besides, an improved maximum sensitivity (S = 820 nm/RIU) is also achieved for bulk refractive index change in surroundings. As a chemical sensor, very low detection limit (DL = 6.1 × 106 RIU) also can be possible to achieve by this device. All the numerical investigations and optimizations were carried out in frequency domain by a numerically efficient and rigorous full vectorial H-field based 2-D and 3-D finite element methods (FEM). A 3D-FEM code is developed and used to find out the wavelength dependencies of the resonator. Possibility of easy CMOS fabrication and integration opportunities make this structure as a prospective and efficient lab-on-chip device