The Effect of Optical Fiber Core and Cladding Diameter on the Loss Added by Packaging and Thermal Cycling

T h e Bell System's Atlanta fiber system experiment 1 in 1976 and Chicago lightwave communications project 2,3 in 1977 to 1979 both used optical fibers with 110-jnm cladding diameter and 55-/im core diameter. In 1979, an experimental investigation was conducted into the effect of core and cladding diameter on the loss added by packaging and thermal cycling. T h e results of that study are reported here. These results contributed to the adoption of 125-jum/50-/Lim fiber dimensions for the Bell system's new FT3 metropolitan trunk lightwave system. 4,5 T h e conflicting requirements on the core diameter (a) and the cladding diameter (rf) are summarized in Table I. This study is directed at items 1 and 2 of Table I. Items 3 (at least for lasers) and 4 are somewhat more difficult to quantify, and will not be addressed here. 859 Table I--Requirements on dimensions Design Consideration 1. 2. 3. 4. Splice Loss Microbending Loss Source Coupling Efficiency Cost Dictates that Dictates that a be d be large small large small -- large -- small