Splice loss in single- and twin-core buried channel waveguide devices

We quantify the magnitude of the power loss incurred when a square-core buried channel waveguide (BCW) is spliced to a standard circular-core telecommunications fibre. With a view to minimizing the dissipated power, we show that a simple equal-core-area criterion provides an elegant means of determining the optimum core dimensions. This result is found to hold for more general BCW cross-sections that possess a reasonable degree of symmetry. The fundamental problems of waveguide misalignment and angular tilt are also investigated and their effect on splice loss is quantified. Our theoretical model is applied to both single- and twin-core waveguides.