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.