Simple method for estimating usable bend radii of deeply etched optical rib waveguides

The successful application of OEIC's requires monomode waveguides, compact low-loss bends, and efficient fiber coupling. The deeply etched rib waveguide shown in Fig. 1 can meet these requirements.1,2 A numerical analysis of the bending loss requires involved calculations such as the three-dimensional BPM3 or the VCM.4 Here, a simple model based on the effective index method (EIM) is introduced that estimates the minimum useable bend radius. Our method does not provide the same degree of accuracy nor a value of the bending loss but does provide an extremely rapid and simple estimate of the minimum useable radius which is all that is required for most design purposes.