Slot-waveguide biochemical sensor

We report an experimental demonstration of an integrated biochemical sensor based on a slot-waveguide microring resonator. The microresonator is fabricated on a ${\mathrm{Si}}_3{\mathrm{N}}_4–\mathrm{Si}{\mathrm{O}}_2$ platform and operates at a wavelength of $1.3\mu \mathrm{m}$. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from $n=1.33$ to 1.42. A linear shift of the resonant wavelength with increasing ambient refractive index of $212\mathrm{nm}$/refractive index units (RIU) is observed. The sensor detects a minimal refractive index variation of $2\times {10}^{-4}\mathrm{RIU}$.