Refractive index sensitivity of a polymer-clad silica optical fiber structure effectively tuned by plasma deposited diamond-like carbon nano-coating

Abstract

Fabrication procedure and refractive index (RI) sensitivity of a diamond-like carbon (DLC) nano-coated optical fiber sensing structure is presented. The overlays were deposited by Radio Frequency Plasma Assisted Chemical Vapor Deposition (RF PACVD) method on both cores of a polymer-clad silica (PCS) multimode optical fibers and oxidized silicon wafers. It is shown that thin (120 to 330 nm in thickness measured on the silicon wafers) and high refractive index (∼2.14 at λ=620 nm) overlays can effectively modify optical response of the structures to variation of the external RI. By deposition of the overlay we achieved 5-times increase in the RI sensitivity of the investigated samples. © 2012 The Authors. Published by Elsevier Ltd.