Nanoscale torsion-free photonic crystal pressure sensor with ultra-high sensitivity based on side-coupled piston-type microcavity

• We propose a novel nanoscale torsion-free photonic crystal pressure sensor and sensor array.
• The dependence of optical properties of resonant mode on the applied pressure is systematically studied.
• Linear relationships between the applied pressure and the shift in the resonant wavelength of the cavity are obtained.
• The pressure sensitivity of 0.50 nm/nN and the minimum detectable pressure variation of 0.68 nN is observed.

A novel nanoscale torsion-free photonic crystal pressure sensor is demonstrated and its performances are theoretically investigated. The proposed sensor device consists of PhC waveguide and side-coupled piston-type microcacity. By using finite-element method (FEM) and three dimensional finite difference time domain technologies (3D-FDTD), the dependence of optical properties of resonant mode on the applied strain is systematically studied. Linear relationships between the applied strain and the shift in the resonant wavelength of the cavity are obtained. The pressure sensitivity as high as 0.50 nm/nN is observed. The minimum detectable pressure variation is estimated to be as small as 0.68 nN. Compared to ring-resonator based pressure sensor achieved an equivalent sensitivity, the sensor size presented in this work is reduced by three orders of magnitude. In addition, a flexible design of pressure sensor array is demonstrated in the end.