Fibre geometry and pigtailing

Packaging, and in particular pigtailing, is becoming an increasingly important issue as optical networks move from the WAN domain to the LAN domain with a resultant pressure to increase production and reduce cost. Variations in fibre geometry (core/cladding diameter, eccentricity) have significant impact on several aspects of pigtailing. In this paper we analyse the effects of these imperfections on a number of issues. In the passive alignment of fibres to waveguides using integral V-grooves, fibre diameter becomes an important parameter. We calculate the tolerances required to meet certain specifications. We also look at how variations in core diameter (which cause a variation in numerical aperture) affect the optimum distance for coupling.