Design of an ultra-compact slotted photonic crystal nanobeam cavity for biosensing

Here, we elucidate a novel biosensor in aqueous environments based on a slotted photonic crystal nanobeam cavity. A slot is introduced in the center of the photonic crystal nanobeam cavity, which reduces the mode volume by an order of 10 without sacrificing the quality factor and sensitivity. This sensor is characteristic of an ultra-small mode volume of 0.076(λ/n)3 and shows a prominent advantage in regards to single nanoparticle detection, where the minimum detectable nanoparticle radius is around 1 nm. Additionally, its quality factor is as high as 6.08×106 and its sensitivity is around 460 nm/RIU, which is promising for refractive index sensing. This sensor can also be integrated into a high-density array of sensor networks because of the unparalleled fabrication advantages.