Carbon-coated fiber Fabry-Perot sensor for harsh environments

Abstract

Carbon coatings on optical sensors can protect them from being corroded by H₂ and H₂O. In this paper, a laserinduced chemical vapor deposition device is presented to grow carbon films on the fiber Fabry-Perot sensor. The scanning electron microscopy and Raman spectroscopy are used to analyze hermetic properties of the carbon coating. Experimental results demonstrated that the carbon-coated sensor exhibited a good long-term stability in a 72MPa and 300°C environment. The fluctuation of the cavity length is only 1nm during seven months after a short-term decrease.