Recent advances in multilayer polymeric interference reflector products

Abstract

Multilayer polymeric interference reflectors possess a number of attributes that are distinctly different from the classical vacuum coated genre of interference reflectors such as: they have large birefringence well-suited to control polarization and designed angle-dependent reflectivity; they come in the form of tough and flexible films, and hence do not require a separate substrate; they are thermo-formable; and are intrinsically scaled for large-area applications. The polymeric multilayer stacks are fabricated by co-extrusion of all layers in one step, with melt processing equipment of the sort used in polyester film making but combined with specialized layer generation hardware. Recent advances in layer thickness control and areal uniformity have enabled numerous product applications requiring more complex spectral forms. Examples presented in this paper include broadband partial reflectors that have monotonically increasing, equal reflectivity for s and p-polarized light as a function of incidence angle, and recent developments in the area of narrow-band visible comb filters for 3D Cinema applications. An overview of layer thickness designs for various applications is presented along with the typical index sets that are achievable with commonly available polymers.