G.657.A2 single-mode fibres optimizing FTTH applications (OSP access & building cabling)

Inhalt:
ITU-T’s Recommendation G.657 represents "Characteristics of a bending-loss insensitive single-mode optical fibre and cable for the access network". From its start this recommendation for bendinsensitive Single Mode Fibres (BI-SMF) has been in the centre point of interest for operators and industry, involved in the roll out of Fibre-to-the-Home (FTTH) networks. Due to the dense distribution, the limited space and the many manipulations in the access network, fibre and cable applied here need different optimization compared to use in a general transport network. Developed in only two years, the first publication of this recommendation took place in 2006, followed by a second edition published in 2009. This paper will highlight the further developments concerning this recommendation as well as ongoing matters discussed in the current revision process. Next focussing on G.657.A2 sub-category BI-SMFs two aspects will be discussed namely splice compatibility and reduced coating diameter. Besides improved macro-bending G.657.A2 BI-SMF also offer improved micro-bending performance, which has been used to optimize new reduced coating diameter fibres (200 µm diameter in stead of regular 250 µm diameter). Such fibres are used in high-fibre-count small-diameter FTTH access cables, very attractive for use in overcrowded ducts of large cities. The characterisation of such 200 µm diameter BI-SMF will be described in this paper.