Radius vertical graded nanoscale interlaced-coupled photonic crystal sensors array

•A radius vertical graded photonic crystal sensors array is proposed.•The five resonant cavities including three H1 cavities and two L2 cavities.•The refractive index sensitivity is 100nm/RIU.•The quality factors of microcavities are over 104.•The sensors array is suited to ultracompact optical monolithic integration.

A radius vertical graded photonic crystal sensors array based on a monolithic substrate is proposed, which is potentially to be used as label-free detection in aqueous environments. The sensors array device consists of five resonant cavities including three H1 cavities and two L2 cavities which are interlaced-coupled to a radius vertical graded single photonic crystal line defect waveguide (W1). Each resonator has a different resonant wavelength dip which can shift independently with crosstalk lower than −13 dB in response to the refractive index change of air holes around every cavity. With three-dimensional finite-difference time-domain (3D-FDTD) method, simulation results demonstrate that the quality factors of microcavities are over 104. Besides, the refractive index sensitivity is 100 nm/RIU with the detection limit approximately of 5.63×10−4. Meanwhile, the radius vertical graded photonic crystal with more interlaced cavities is more suited to ultracompact optical monolithic integration.