Silicon optical fiber pressure sensor

A novel optical fiber pressure sensor based on a micromachined thin silicon diaphragm is proposed. Detail descriptions of the sensor structure, modulation principle and fabrication process are given. The device operates on the following principle: Pressure deflects a silicon diaphragm which moves the output end of a light source fiber. The emitted light intensity is picked up and shared by two receiving fibers placed side by side. The variation of the intensity ratio in the receiving fibers caused by the relative motion of the emitting fiber can be easily converted to a linear signal versus the deflection of the silicon diaphragm. This ratio is independent of the light source intensity so that fluctuations of a light source is automatically compensated. Having advantages of both a silicon sensor and a optical fiber sensor, such as compactness and immunity to electromagnetic field, the sensor works with good linearity and sensitivity