High sensitivity extrinsic Fabry-Pèrot interferometer for humidity sensing

In this work we present a high sensitivity optical fiber humidity sensor. The configuration chosen for this purpose is a Fabry-Pérot interferometer. The device has been fabricated by means of sputtering. A semiconductor material was used to build the nano-cavity which produces the interferometry. Then the device was introduced into a climatic chamber in order to change relative humidity. Changes of 88 nm have been obtained for relative humidity varying from 20% to 90%, which implies a sensitivity of 1.27 nm/%RH.