An interface between two different optical materials can comprise a stack of thin film layers that manage light incident on that interface. One of the optical materials can have a first composition and a first refractive index, while the other optical material can have a second composition and a second refractive index. The stack can comprise thin film layers of the first optical material interleaved between thin film layers of the second optical material. The layers of the stack can be configured to provide the stack with an aggregate composition of at least one of the optical materials that progressively varies from one end of the stack to the other end. To provide the progressive variation in composition, the layers of one of the optical materials can have a progressively increased thickness across the stack, or can progressively increase in number, for example.