New design for a variable optical attenuator based on a bent channel waveguide

We present a new method for bend loss control in a curved channel optical waveguide and employ it in a novel design of a thermo-optic variable optical attenuator. We show that the introduced asymmetric refractive index profile of the waveguide structure, combined with the optimal placement of the heating electrodes, leads to a significant increase of the dynamic range of the attenuator. PACS 42.82.Et; 42.70.Jk; 42.79.Ta