Suppression of parasitic interference in a fiber-tip Fabry-Perot interferometer for high-pressure measurements.

We demonstrate a novel design and fabrication process for fiber-tip Fabry-Perot interferometric (FTFPI) pressure sensors which eliminates fringe envelopes in the reflection spectrum. The outer facet reflectivity and thickness of the FTFPI silica diaphragm were reduced through orthogonal rough-polishing of the fiber end facet. A silica FTFPI sample with a diaphragm thickness of ~10.7 μm was produced and tested under hydraulic pressures ranging from 0 to 30 MPa. The proposed sensor achieved a pressure sensitivity of -284 pm/MPa at 1555 nm and could be a valuable new tool for high pressure measurements.