Photonic crystal stress sensor with high sensitivity in double directions based on shoulder-coupled aslant nanocavity

In this paper, we demonstrate a photonic crystal (PhC) stress sensor with high sensitivity in two orthogonal directions. The stress sensor consists of an aslant lattice-shifted resonant cavity shoulder-coupled to two terminated Γ–K waveguides. The linear relationship between the shifts of resonant wavelength and applied stress in double directions is calculated with the finite element method (FEM) and finite difference time domain (FDTD) simulations. With the simulations, we demonstrate that the stress sensitivity of 7.5 nm/μN in horizontal direction and 10 nm/μN in vertical direction is achieved, respectively, and a stress detection limit is approximately of 58 nN and 44 nN in horizontal and vertical direction for this device, respectively.