Design of large-mode-area single-mode optical fiber with lowing bending loss for Raman distributed temperature sensor

Numerical investigation on the design of a large-mode-area (LMA) single-mode photonic crystal fiber (PCF) as the sensing fiber for Raman distributed temperature sensor (DTS) is presented. The PCF can enable single-mode operation and have an extremely LMA exceeding 288 μm2 when kept straight and over 284 μm2 with a lower bending loss of 0.25 dB/m when bent over a 5 cm radius at a wavelength of 1550 nm. We outline the principles of our fiber design and explore the unique properties of the fiber for Raman DTS. Calculation results show that the Raman DTS system, which used the proposed PCF as the sensing fiber, can improve SNR about 3.4 times by increasing the input power compared with the Raman DTS system with a conventional single-mode fiber, because of the improved LMA, single-mode operation and good bending characteristics of the PCF.