Extreme Radiation Sensitivity of Ultra-Low Loss Pure-Silica-Core Optical Fibers at Low Dose Levels and Infrared Wavelengths.

Adriana Morana,Cosimo Campanella,Imène Reghioua,Aziz Boukenter,Philippe Paillet,Vincenzo De Michele,Jeoffray Vidalot,Sylvain Girard,Youcef Ouerdane,Emmanuel Marin

doi:10.3390/s20247254

Abstract

We report here the response of a commercial ultra-low loss (ULL) single-mode (SM) pure silica core (PSC) fiber, the Vascade EX1000 fiber from Corning, associated with 0.16 dB/km losses at 1.55 µm to 40 keV X-rays at room temperature. Today, among all fiber types, the PSC or F-doped ones have been demonstrated to be the most tolerant to the radiation induced attenuation (RIA) phenomenon and are usually used to design radiation-hardened data links or fiber-based point or distributed sensors. The here investigated ULL-PSC showed, instead, surprisingly high RIA levels of ~3000 dB/km at 1310 nm and ~2000 dB/km at 1550 nm at a limited dose of 2 kGy(SiO2), exceeding the RIA measured in the P-doped SM fibers used for dosimetry for doses of ~500 Gy. Moreover, its RIA increased as a function of the dose with a saturation tendency at larger doses and quickly recovered after irradiation. Our study on the silica structure suggests that the very specific manufacturing process of the ULL-PSC fibers applied to reduce their intrinsic attenuation makes them highly vulnerable to radiations even at low doses. From the application point of view, this fiber cannot be used for data transfer or sensing in harsh environments, except as a very efficient radiation detector or beam monitor.

Highlights

Optical fiber manufacturers are increasingly interested in developing single-mode waveguides with ultra-low loss at telecom wavelengths in order to guarantee the infrared (IR) signal transmission along hundreds of kilometers in submarine networks, minimizing the need for costly optical repeaters.A few years ago, most commercial Telecom-grade fibers had a Ge-doped silica core and a cladding in pure or slightly doped silica such as the Corning® SMF-28TM, which is the standard for data transfer and today has been mainly replaced by Corning® SMF-28e+ [1]
We focused our attention on the radiation induced attenuation (RIA) in an ultra-low loss pure silica core (ULL-PSC) optical fiber
As already observed in [6], the P-doped optical fibers (OFs) losses at 1550 nm increased linearly as a function of the dose up to ~500 Gy: up to this total ionizing dose (TID), the slope was about 4 dB km−1 Gy−1, whereas the sensitivity coefficient started decreasing at higher doses

Summary

Introduction

A few years ago, most commercial Telecom-grade fibers had a Ge-doped silica core and a cladding in pure or slightly doped silica such as the Corning® SMF-28TM, which is the standard for data transfer and today has been mainly replaced by Corning® SMF-28e+ [1]. Such optical fibers (OFs) have typical attenuation levels slightly above 0.2 dB/km at 1550 nm, the Rayleigh scattering being the main origin of these optical losses. Efforts are mandatory to achieve a very specific manufacturing process, allowing the decrease in glass density fluctuation and the associated losses in order to achieve the so-called ultra-low loss (ULL) optical fibers [2]

Methods

Results

Conclusion