Highly sensitive fiber pressure sensor based on off-center diaphragm reflection

A fiber pressure sensor with a collimator at the off-center position of a diaphragm is demonstrated. The detection mechanism is incident-angle sensitive rather than traditional working-distance sensitive. Due to the small beam divergence of the collimator, the control on working distance is less stringent, and high sensitivity can be realized because the coupling efficiency of the collimator is very sensitive to the incident angle decided by the off-center diaphragm reflection. Sensitivity of 1.11 and 0.16 dB/KPa can be achieved with silicon diaphragm thicknesses of 100 and 150 μm, respectively. Moreover, the detection range can be continually shifted by changing the pressure in the sealed diaphragm cavity.