Effect of added layers on bend loss in buried channel waveguides

We propose a number of ways to control bend loss in buried channel waveguides. They are based on the introduction of additional layers with slightly different indices in the cladding. In some applications, such as switching or sensing, it may be important to increase the bend loss in the ´active´ regime without increasing it in the ´passive´ regime. An improved design of a variable optical attenuator, based on a bent channel waveguide, is presented as an example of applying this strategy.