Optical fiber vector flow sensor based on a silicon Fabry-Perot interferometer array.

We report a miniature fiber-optic water vector flow sensor based on an array of silicon Fabry-Perot interferometers (FPIs). The flow sensor is composed of four silicon FPIs, one in the center with the other three equally distributed around it. The center FPI is heated by a cw laser at 980 nm, which is guided through the lead-in single mode fiber. The temperature structure established within the sensor head due to laser heating is a function of the flow vector (speed and direction), which can be deduced from the wavelength shifts of the four FPIs. Theoretical analysis has been conducted to illustrate the operating principle and experimental demonstration has been provided.