Analysis of worst-case fiber splice loss associated with mechanical tolerance

An analysis is presented of optical fiber splice loss associated with mechanical tolerance for coated and uncoated avionic fibers coupled in a loose sleeve (glass capillary). A simple prescription is provided for calculating worst-case loss, combining simultaneous contributions from core offset, core diameter mismatch, numerical aperture mismatch, and core ellipticity. Worst-case values are interpreted with the aid of a Monte Carlo analysis, simulating 10,000 splices. The analysis produces a simple rule of thumb relating the worst-case splice loss to the value exceeded by 1% of the simulated splices: "divide the worst-case loss by 3 to get the 1% value.".