Fiber ring laser for axial micro-strain measurement by employing few-mode concentric ring core fiber

We proposed and demonstrated a novel few-mode concentric-ring core fiber (FM-CRCF) for axial microstrain measurement with fiber ring laser based on few-mode-singlemode-few-mode fiber structure. The core area of CRCF consists of four concentric rings which refractive indices are 1.448, 1.441, 1.450, 1.441, respectively. LP01 and LP11 are two dominated propagating mode groups contributing in the CRCF. In this few-mode-singlemode-few-mode structure, two sections of CRCF act as the mode generator and coupler, respectively. The basis of sensing is the center single mode fiber. Moreover, this structure can be used as an optical band-pass filter. By using fiber ring cavity laser, the axial micro-strain sensing system has high intensity (similar to 20 dB), high optical signal to noise ratio (similar to 45 dB) and narrow 3 dB bandwidth (similar to 0.1 nm). In the axial micro-strain range from 0 to 1467 mu epsilon, the lasing peak wavelength shifts from 1561.05 nm to 1559.9 nm with the experimentally sensitivity of similar to 0: 81 pm/mu epsilon. (C) 2016 Elsevier Inc. All rights reserved.