WCA March 2014

New coating for mid temperature optical fibres By Ching-Kee Chien and Valery A Kozlov, Science and Technology, Corning Inc, USA

Abstract UV cured acrylate type coating materials for mid-temperature optical fibres (operating temperatures up to +200°C) are considered as a replacement for the existing silicone type coating materials due to better manufacturability and handling (stripping, cleaning and re-coating) properties. A newly developed coating material demonstrated superior performance in comparison with the existing commercial mid-temperature acrylates. Long-term temperature aging of several fibre samples was used to study fibre performance at elevated temperatures. Optical attenuation and fibre strength were measured at different conditions to confirm the excellent performance and durability of the new material. 1 Introduction Telecom grade UV cured acrylate coating materials for optical fibres are good for operating temperatures up to 85°C in long-term applications but suffer non-reversible degradation at higher temperatures for prolonged periods. Today several commercial UV cured acrylate type coating materials, including primary and secondary ones, are available for mid-temperature applications at 150°C–180°C. 1-4 Single or dual coat designs are available. Temperature aging of optical fibre by temperature cycling or constant temperature in normal atmosphere is the primary experimental method to track coating stability and to test optical fibre parameters: attenuation and mechanical strength. Dynamic thermo gravimetric analysis (TGA) and isothermal TGA are used to compare different coating materials, estimate coating material lifetime based on coating weight loss, and to define the best coating system for a specific application. Corning Incorporated has evaluated a new optical fibre coating material for mid-temperature applications. The coating is a UV-cured acrylate type material. This material should preserve long-term optical fibre performance for bare and cabled fibre.

New Commercial

TGA weight, %

Temperature, °C

❍ ❍ Figure 1 : TGA test of the new and commercial mid- temperature coatings at heating rate of 10°C/min

New Commercial

Weight loss, %

❍ ❍ Figure 2 : TGA test for single coat fibre sample with new and commercial materials at heating rate of 20°C/min Temperature, °C The new coating delivers a high coating adhesion to glass, which is highly desirable in some mid-temperature optical fibre applications for better handle ability and optical performance. 2 New coating material 2.1 Material properties The newly developed mid-temperature coating is a UV curable urethane acrylate. A 75-micron thick film cured at 1 J/cm 2 with Fusion D-bulb was measured by a Seiko

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