Photonic crystal based all-optical pressure sensor

This paper presents the first-ever vertical silicon nanowire array based all-optical pressure sensor. Vertical silicon nanowire arrays with photonic crystal structure, can selectively trap or diffract light, depending on the optical wavelength, nanowire diameter, and nanowire pitch spacing. Here, we realize an all-optical pressure sensor by fabricating controllable vertical silicon nanowire arrays on a Si/SiO₂ membrane. Applying hydrostatic pressure bends the membrane, leading to membrane color change due to the modulation of the nanowire pitch and deflection angle. By acquiring the membrane image with a camera, the color image can be cross-correlated with a calibration data set to calculate pressure.