Calculation of bending losses for highly confined modes of optical waveguides with transformation optics.

We revisited the fundamental problem of bending loss calculation in optical waveguide theory using transformation optics (TOs). Due to the fact that TOs is based on the form invariance property of Maxwell equations, this new approach provides more accurate calculation of waveguide bending loss compared to the conventional refractive index conformal mapping method, especially for small bending radii typical for plasmonic waveguides or photonic waveguides with high-index contrast. We believe our results provide a simple yet reliable way of bending loss calculation for highly confined optical (including plasmonic) waveguides.