Miniature Temperature Compensated Fabry–Perot Pressure Sensors Created With Self-Aligned Polymer Photolithography Process

We present a cross-axial and a co-axial miniature Fabry-Perot pressure sensor fabricated at the tip of an optical fiber with a prewritten Bragg grating by using maskless photolithography process and UV curing polymer process. The optical fiber serves as an intrinsic mask for sensor fabrication as well as a waveguide for sensor interrogation. A polymer-metal composite thin diaphragm is employed as the pressure transducer. The overall sensor size is almost the same as that of a standard single mode optical fiber. Experimental study shows that the sensors exhibit good linearity over a pressure range of 1.9- 9.4 psi , with sensitivities of and psi for the cross-axial and co-axial sensors, respectively. The fiber Bragg grating is exploited for simultaneous temperature measurements or to compensate for temperature effects in pressure readings. The dynamic response of the sensors is also evaluated and discussed. These sensors are expected to impact many fronts that require miniature and inexpensive sensors for reliable static and transient pressure measurements of fluids.