Index insensitive micro-strain sensor based on hollow core photonic crystal fiber

In this paper, application of a Hollow Core Photonic Crystal Fiber (HC-PCF) as a micro-strain sensor has been demonstrated. Two different designs of HC-PCF with different core diameters (large core PCF and small core PCF) have been investigated for different strain levels ranging from 0 mu epsilon to 2000 mu epsilon at the wavelength, 1550 nm. High strain sensitivities of 3.71 pm/mu epsilon and 2.3 pm/mu epsilon have been achieved for the large core PCF and small core PCF, respectively. Also, due to the special air-hole structure of HC-PCF, the sensitivity of strain measurement remains unaffected of the changes in Surrounding Refractive Index (SRI).